Australian Defence Force planes are on their way to Tonga to assess damage from the air and deliver crucial supplies to the ground, after the weekend's massive volcano eruption in the Pacific.

A thick cloud of Volcanic Ash, which spewed as high as 20 kilometres into the air, delayed the flights from the Royal Australian Air Force base in Ipswich, west of Brisbane this morning.

Treasurer Josh Frydenberg said the surveillance flights over Tonga would help identify damage on roads, ports and critical infrastructure.

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With internet and phone lines down, friends and family members around the world were left anxiously trying to get in touch.

Government websites and other official sources have remained without updates today.

"Tonga is a close friend and partner of Australia," Mr Frydenberg said.

"It's part of that Pacific family."

The Australian airforce will work in tandem with counterparts from New Zealand, he said.

HMAS Adelaide, currently at port in Sydney, is reportedly being deployed to Brisbane where it will be loaded with supplies for Tonga.

Fiji, a close neighbour in the Pacific, also suffered bad damage.

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New Zealand Prime Minister Jacinda Ardern there had not yet been any official reports of injuries or deaths, but cautioned authorities hadn't yet made contact with some coastal areas and smaller islands.

She said there had been significant damage to boats and shops along the Tongan coastline.

The capital, Nuku'alofa, was covered in a thick film of volcanic dust, Ms Ardern said, contaminating water supplies and making fresh water a vital need.

Aid agencies said thick ash and smoke had prompted authorities to ask people to wear masks and drink bottled water.

In a video posted on Facebook, Nightingale Filihia was sheltering at her family's home from a rain of volcanic ash and tiny pieces of rock that turned the sky pitch black.

"It's really bad. They told us to stay indoors and cover our doors and windows because it's dangerous," she said.

"I felt sorry for the people. Everyone just froze when the explosion happened. We rushed home."

Outside the house, people were seen carrying umbrellas for protection.

One complicating factor to any international aid effort is that Tonga has so far managed to avoid any outbreaks of COVID-19.

The true magnitude of the volcano has yet to be confirmed.

Initially, it was estimated the plume of ash climbed 20km-high, but some reports today suggested it could be 30km.

There were also some unconfirmed reports of a second explosion just before noon (AEST), but it appeared unfounded.

https://twitter.com/WeatherWatchNZ/status/1482876643819810816

A New Zealand meteorological service posted six hours of satellite footage taken from above Tonga this morning, in an effort to try and clarify the reports.

"Earthquakes possibly," it said in a Twitter post paired with moving satellite imagery.

"But nothing visible showing up as a big eruption.

"Normal tropical clouds showing up, perhaps a very small eruption."

With Associated Press