At least 11,300 people have died and another 10,100 are missing from the coastal city of Derna a week after Storm Daniel hit north-eastern Libya.

The United Nations Office for the Co-ordination of Humanitarian Affairs reported on Saturday an estimated 170 people have been killed as a result of the flooding elsewhere in the country, and more than 40,000 people have been displaced, citing the latest data from International Organisation for Migration.

Figures are expected to rise as the search for the missing continues and more bodies are pulled from the sea.

Central Street, once a focus of economic activity in Derna lined with shops, was largely deserted on Saturday, the silence broken only by the sound of the wind whistling past mangled buildings as a few people sat disconsolate in the road, sipping coffee and surveying the damage.

“The first thing I’m afraid of is that this will take a long time,” said 44-year-old teacher Tarek Faheem al-Hasadi, whose wife and five young grandchildren were killed in the flood.

He and his son survived by climbing onto the roof.

“This needs persistence and I’m afraid that the support that is coming is temporary,” he said between tears, standing guard in front his ruined home, but adding that he was determined not to leave the area.

A three-storey building standing opposite had been swept 60 metres down the road by the flood waters, Hasadi said.

At Derna’s seafront, where a wrecked car could be seen perched on top of concrete storm breakers and driftwood was strewn across muddy pools, diggers worked to clear the path for rescue teams and a helicopter scanned the sea for bodies.

Entire districts of Derna, with an estimated population of at least 120,000, were swept away or buried in brown mud after two dams south of the city broke last Sunday, unleashing torrents of floodwater down a usually dry riverbed.

“The situation is very, very tragic,” said Qais, a rescue worker from Tunisia at the seafront who only gave his first name.

“We have never seen such damage caused by water.”

More than 450 bodies have been recovered in the past three days from the seashore, including 10 from under the rubble, said Kamal Al-Siwi, the official in charge of missing people.

“The work is ongoing and is very, very, very complicated,” he told Reuters.

“This operation in my opinion, needs months and years.”

The World Health Organisation said on Saturday it had flown in enough emergency aid to reach almost 250,000 people affected by Storm Daniel across eastern Libya, including essential medicines, surgery supplies and body bags for the deceased.

Saudi Arabia announced the departure of its first aid flight to Libya and Russia said the third of its aid flights had arrived carrying a mobile hospital.

An Italian naval ship docked in Derna with supplies including tents, blankets, water pumps and tractors, Italy’s Embassy in Libya said, posting photos of smaller vessels bringing equipment ashore.

More than 1000 people have been buried in mass graves, according to the UN, drawing warnings from aid groups about the risk of contaminating water or causing mental distress to families of the deceased.

The head of Libya’s National Centre for Disease Control, Hayder Al-Sayah, said there was little risk from corpses unless they were carrying diseases, but that recorded cases of diarrhoea had risen to 150 from 55 on Friday due to people drinking polluted water.