Video posted by the Guardian’s Shaun Walker shows the devastation wrought by the Russian campaign against the town of Mariupol:

There have been a number of reports that Ukrainian forces have retaken a number of towns across the country.

The Kyiv Independent newspaper reported that two small towns, Poltavka and Malynivka, in the south-eastern region of Zaporizhzhia had been liberated while earlier it reported that the town of Trostyanets in the northern region of Sumy had been regained.

CNN also reports that it has geolocated and verified several videos showing Ukrainian troops back in control of a number of villages in Sumy as well as Vilkhivka, a settlement roughly 32 kilometres from the Russian border in Ukraine’s northeast.

Some images from around Ukraine on Saturday:

Here’s a bit more from Ukrainian president Zelenskiy’s speech earlier, in which he warned Russia its invasion was only working to “derussify” Ukraine, where Russian is widely spoken.

By the way, we talked today with our military in Mariupol, with our heroes who defend this city, in Russian,” said the president, himself a native Russian speaker.

“Because there is no language problem in Ukraine and there never was.

But now you, the Russian occupiers, are creating this problem. You are doing everything to make our people stop speaking Russian themselves. Because the Russian language will be associated with you. Only with you.

With these explosions and killings. With your crimes. You are deporting our people. You are bullying our teachers, forcing them to repeat everything after your propagandists. You are taking our mayors and Ukrainian activists hostage. You are placing billboards in the occupied territories with appeals (they appeared today) not to be afraid to speak Russian.

Just think about what it means. Where Russian has always been a part of everyday life, like Ukrainian, in the east of our state, and where you are turning peaceful cities into ruins today.

Russia itself is doing everything to ensure that de-russification takes place on the territory of our state. You are doing it. In one generation. And forever. This is another manifestation of your suicide policy.”

The International Atomic Energy Agency has expressed concern for workers at the Chernobyl nuclear power plant, after Russian forces on Saturday seized the town of Slavutych, where many people who work at the reactor live.

In a statement, the agency said director general Rafael Mariano Grossi,

Remained concerned about the ability of staff at the Chornobyl NPP to regularly rotate and return to their homes in the nearby city of Slavutych to rest. There has been no staff rotation at the NPP for nearly a week now, the [Ukrainian] regulator said …

The regulator said the last staff rotation was on 20-21 March, when a new shift of technical personnel arrived from Slavutych to replace colleagues who had worked at the Chornobyl NPP since the day before the Russian military entered the site, where radioactive waste management facilities are located. There was ‘no information when or whether’ a new change of work shift would take place, it said.

In the north-eastern city of Kharkiv, where a nuclear research facility has reportedly been damaged once again, the IAEA cited the Ukrainian regulator as saying “shelling was for a second day preventing measures to dispose of an unexploded [nearby] rocket”.

“Its nuclear material is subcritical and the radioactive inventory is low,” the IAEA continued. “Personnel at the facility were maintaining the operability of the nuclear installation’s equipment and radiation was within ‘standard limits’. However, it was not possible to restore off-site power to the facility due to the shelling, the regulator added.”

After the White House backpedalled on comments by president Joe Biden that appeared to call for regime change in Russia, prominent Putin critic and chess grandmaster Garry Kasparov has called the US administration “pathetic”.

When a regime is repressive, murderous, dictatorial, and led by someone who has committed war crimes in multiple countries, including his own, what else should be hoped for and worked toward than regime change?” he wrote in the first of a series of tweets.

“When the President is right, the White House should stick with him instead of fumbling to apologize to a murderous dictator for speaking the truth. It’s pathetic,” he continued.

“Biden isn’t Trump, requiring an English to English translator! No dictator is legitimate. Don’t backpedal when you are right and in the right. Don’t play diplomatic games with a mass murderer.”

In a possible shift on a plan to transfer Soviet-era fighter jets from Poland to Kyiv to boost Ukraine’s firepower in the skies – rejected earlier this month by the Pentagon as too not “tenable” – Ukraine’s foreign minister, Dmytro Kuleba, says the US no longer objects, according to AFP.

“As far as we can conclude, the ball is now on the Polish side,” Kuleba said in written comments to the newswire after a meeting with US president Joe Biden in Warsaw.

Biden, who was winding up a whirlwind visit to Poland after holding a series of urgent summits in Brussels with Western allies, met both Kuleba and Ukrainian defence minister Oleksii Reznikov in an emphatic show of support for Kyiv.

Both ministers had made a rare trip out of Ukraine for the face-to-face talks, in a possible sign of growing confidence in their battle against Russian forces.

In the UK Ministry of Defence’s latest intelligence update, it says Russia has continued strikes across Ukraine, including on “many targets in densely populated civilian areas”.

It also said Russia continued to rely on so-called stand-off munitions – missiles launched from a distance – “in order to reduce their aircrafts’ exposure to Ukrainian air defence forces.”

“US reporting of up to 60% failure rates of these weapons will compound Russia’s problem of increasingly limited stocks forcing them to revert to less sophisticated missiles or accepting more risk to their aircraft,” it continued.

An updated tally on the total deaths of civilians in Ukraine thus far, according to the United Nations:

It is 1am in Ukraine and Ukrainian troops are reporting that Russian forces are deploying white phosphorus against them near the eastern city of Avdiivka.

While these reports can’t be confirmed, this is not the first time Ukraine has talked about Russia using white phosphorus in the invasion. This week, Volodymyr Zelenskiy told Nato leaders that “there were phosphorus bombs, phosphorus Russian bombs”. “Adults were killed again and children were killed again,” he said.

White phosphorus is used in war for a number of reasons – when a munition containing it explodes, the chemical inside creates a thick white cloud that many countries have utilized as a way to create a smokescreen for cover or to send a signal to troops.

But white phosphorous burns at the extremely high temperature of 800C or above, meaning that it could burn straight through to the bone if it were to come into contact with human flesh. It can also enter the bloodstream with prolonged exposure and poison organs such as the heart, liver and kidneys and cause multiple organ failure. The smoke created by the substance itself can also damage the lungs.

When asked about Zelenskiy’s comments on Russia using phosphorus bombs, Kremlin spokesman Dmitry Peskov said that Russia “has never violated international conventions”.

For more on if Russia’s possible use chemical weapons – and how Nato would respond – read more here:

Related: Could Russia use chemical weapons in Ukraine and how would west respond?

The Institute of Mass Media in Ukraine has documented 148 crimes against journalists and the media since the start of the Russian invasion:

• 5 journalists killed
• 6 captured or kidnapped
• 7 wounded
• 19 cybercrimes
• 10 shellings of television broadcast towers
• 5 shellings of journalists
• 11 threats
• 6 shutdowns of Ukrainian broadcasting
• 4 blockings of internet access to media
• 4 seizures and attacks on media outlets
• 1 disappearance of a journalist

British foreign minister Liz Truss says the UK could lift sanctions imposed on Russian individuals and companies if Russia withdraws from Ukraine and commits to “no further aggression”, the Telegraph is reporting.

The British government has so far imposed sanctions on banks with total assets of £500bn ($658.65bn) and on oligarchs and family members with a net worth of more than £150bn pounds.

Sanctions could be lifted in the event of “a full ceasefire and withdrawal”, said Truss.

“What we know is that Russia signed up to multiple agreements they simply don’t comply with. So there needs to be hard levers. Of course, sanctions are a hard lever,” she said.

“Those sanctions should only come off with a full ceasefire and withdrawal, but also commitments that there will be no further aggression. And also, there’s the opportunity to have snapback sanctions if there is further aggression in future. That is a real lever that I think can be used.”

In the latest tally on the destruction wrought so far in Ukraine, the Ukraine minister for communities and territories development is reporting that Russian troops have destroyed an estimated 4,500 residential buildings, 100 businesses, 400 educational institutions and 150 health facilities.

Joe Biden sparked some concerns when he said in his fiery speech today in Poland that Vladimir Putin “cannot remain in power”. Some said that statement skewed uncomfortably close to calling for a regime change, despite Biden’s foreign policy being firmly against a US-involved regime change. The White House immediately had to walk his statement back, saying that his point “was that Putin cannot be allowed to exercise power over his neighbors or the region”.

This newest development is sure to raise some eyebrows in Moscow as well: a White House readout said that Biden took a phone call on Air Force One with democratic opposition leader Sviatlana Tsikhanouskaya of Belarus.

During the phone call, Biden thanked Tsikhanouskaya for attending his speech in Warsaw and “underscored the continued support of the United States for the Belarusian people in defending and advancing human rights, including freedom of expression, and free and fair elections”.

Belarus is one of the few allies that Russia has right now. Under Alexander Lukashenko, the president of Belarus, reports of torture and mass arrests of political dissidents have been widespread. In December, Tsikhanouskaya’s husband was sentenced to 18 years in prison for challenging Lukashenko, charged with organizing mass unrest and inciting social hatred as he campaigned to run for president.

Tsikhanouskaya took his place on the ballot in August’s presidential elections that ended in accusations of vote rigging, mass street protests, and a bloody crackdown on opposition.

In Prague today, a striking protest:

Ukrainian prosecutor general Iryna Venediktova has some numbers on journalists who have been killed or injured since the start of the Russian invasion:

Kharkiv is likely Ukraine’s second most-shelled city after Mariupol, with bodies stacked in the courtyard of morgues and missiles and rockets raining down each day.

But its people are resilient, digging deep within themselves to keep the city clean and morale high.

“We are scared, but we need to show people that the situation is under control and every day we are getting closer to victory,” governor Oleh Synyehubov, told the Observer.

Read more about Kharkiv here:

Related: Kharkiv citizens: ‘They can bomb us for as long as they want: we will withstand it’

Update on Slavutych: the mayor of the small town near the Chernobyl site has made an address saying that though the city is now officially under Russian occupation, the city’s residents met its occupiers with a mass protest and vowed to keep the city Ukrainian.

The Ukrainian parliament has confirmed the attack on the nuclear research reactor in Kharkiv.

In Slavutych, a northern town close to the Chernobyl nuclear site, unarmed residents met the incoming Russian troops with a mass protest.

Earlier today, the town of 25,000 residents was surrounded by Russian troops and its mayor, Yuri Fomichev, taken prisoner. After failing to disperse the numerous protesters in the main square on Saturday – despite deploying stun grenades and firing overhead – the Russian troops released the mayor and agreed to leave.

Read more here:

Related: Russian soldiers release Ukraine town’s mayor and agree to leave after protests

An outdoor concert in Lviv was cut short as air raid sirens sounded – and soon afterwards the city was hit by missiles, wounding at least five. Lviv, in western Ukraine, is about 40 miles from the Polish border and has so far been spared the fighting and devastation experienced in cities located closer to Russia.

With the Russian invasion now firmly in its second month, Ukrainians fear that the northern city of Chernihiv will be the next Mariupol when it comes to death and destruction.

The Associated Press is reporting that, just like Mariupol, Chernihiv is similarly blockaded and pounded from afar by Russian troops, leaving the city’s remaining residents terrified with each blast and bodies lying uncollected in the streets.

“In basements at night, everyone is talking about one thing: Chernihiv becoming (the) next Mariupol,” 38-year-old resident Ihar Kazmerchak, a linguistics scholar, told the Associated Press via a cellphone with a dying battery.

“Food is running out, and shelling and bombing doesn’t stop,” he said.

Chernihiv is located between the Desna and Dnieper rivers, straddling one of the main roads that Russian troops invading from Belarus used on 24 February for what the Kremlin hoped would be a quick hit onward to the capital, Kyiv, just 147km (91 miles) away.

More than half of the city’s 280,000 residents have fled, with the mayor, Vladyslav Atroshenko, estimating the death toll from the war to be in the hundreds. This week, Russian bombs destroyed the city’s main bridge over the Desna on the road leading to Kyiv and rendered the remaining pedestrian bridge impassable, thus cutting off the last possible route for people to get out or for food and medical supplies to get in.