A plume of smoke can be seen rising from Hunga-Tonga-Hunga-Ha'apai volcano in images taken before the eruption, with the volcanic island appearing to have all but disappeared afterwards.

The pictures have emerged as Australia and New Zealand sent military surveillance flights to assess damage to the Pacific island nation, efforts which had been delayed due to the towering ash cloud preventing earlier flights.

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Tonga is comprised of 176 islands, only 36 of them inhabited, with a population of just over 104,000 people.

It has been largely cut off from the world after the eruption cut off its undersea communications cable, and repairs will take some time as there is still some volcanic activity in the area.

Evacuations under way and aid dispatched

Tonga said the evacuation of some outlying islands was under way after the destruction of homes, adding that the navy had been deployed with health teams and water, food and tents.

The government also confirmed three deaths, two locals and British national Angela Glover, in its first official update since Saturday's volcanic eruption and tsunami.

A 65-year-old woman on Mango and a 49-year-old man on Nomuka are the other confirmed deaths, while a number of injuries were also reported.

Every home on one of the smaller islands, Mango, where around 50 people live, has been destroyed, the office of Prime Minister Siaosi Sovaleni said in a statement.

Only two houses remained on Fonoifua, and Namuka island had suffered extensive damage.

Tonga's main island Tongatapu has reported "significant infrastructural damage", according to UN spokesman Stephane Dujarric.

Surveillance flights have shown extensive damage to the Ha'apai group of islands [including Mango and Fonoi] and there has been no contact with them, Mr Dujarric said.

Tonga's deputy head of mission in Australia, Curtis Tu'ihalangingie, said pictures taken by the New Zealand Defence Force (NZDF) showed "alarming" scenes of a village destroyed on Mango and buildings missing on Atata island, which is closer to the volcano.

He said: "People panic, people run and get injuries. Possibly there will be more deaths and we just pray that is not the case."

What's the extent of the damage?

According to Tonga's government, 105 people live on Mango and Fonoi.

Photos were released on Facebook from a NZ Defence Force report which shows the extent of damage on some of Tonga's islands. It shows:

• Tonga's capital Nuku'alofa has suffered "limited to moderate" damage, with some flooding and a layer of ash covering buildings and vehicles

• The Ha'apai group of islands - 51 islands, 17 of them inhabited - has had "extensive" damage, with "all but the largest buildings destroyed or severely damaged"

• Mango has suffered "catastrophic" damage, with the entire village having been destroyed

• Only two houses remain on Fonoifua, and Namuka island has suffered extensive damage

• Nearby Atata has also suffered "catastrophic" damage, with many buildings missing

New Zealand's military has sent drinking water and other supplies, but relief efforts have been hampered by thick ash on an airport runway.

The country has also sent two navy ships and has pledged an initial one million New Zealand dollars (£498,000) towards recovery efforts.

Australia said it has sent a naval ship from Sydney to Brisbane, so it can sail for Tonga if the Tongan government requests further help.

These four pictures show the Hunga Tonga Hunga Ha'apai volcano at different stages in the months, weeks, and hours before the eruption:

The UN World Food Program is also exploring how to bring in relief supplies, though one complicating issue is that Tonga has managed to avoid outbreaks of COVID-19.

New Zealand has said its military staff are vaccinated and willing to follow Tonga's protocols.

The family of Ms Glover, 50, said she was swept away by a wave.

Nick Eleini said his sister's body had been found and that her husband survived.

"I understand that this terrible accident came about as they tried to rescue their dogs," Mr Eleini told Sky News.