Planes carrying much-needed humanitarian supplies from Australia and New Zealand are on their way to tsunami-hit Tonga, as the South Pacific island finally made contact with the rest of the world after being cut off for five days.

Australia’s Defence Minister Peter Dutton said a Royal Australian Air Force aircraft loaded with humanitarian supplies and a sweeper to assist in removing ash from the airport runway had left Brisbane and another aircraft would leave later on Thursday.

Hundreds of Tongans have reportedly been sweeping ash from the runway with brooms, after a call to arms across the island nation. But they are hampered because the ash keeps falling.

New Zealand’s foreign minister said on Thursday its air force had also sent a C-130 Hercules from Auckland.

The delivery of supplies will be contactless and the NZ plane is expected to be on the ground for just 90 minutes before it begins its return flight.

Tonga is COVID-free and is concerned that aid personnel may bring in the virus.

The explosion of the Hunga Tonga-Hunga Ha’apai volcano, which has killed at least three people and sent tsunami waves across the Pacific, badly damaging villages, resorts and many buildings in Tonga and knocked out communications of about 105,000 people on Saturday.

Telephone links between Tonga and the wider world began to be reconnected late on Wednesday. However, restoring full internet connectivity is likely to take a month or more, according to the owner of the archipelago’s sole subsea communications cable.

Tweet from @DigicelTO

Meanwhile, Tongans abroad were frantically calling their families back home to ensure their safety.

“Today there’s a sigh of relief as we are able to communicate with our loved ones back home,” said John Pulu, a Tongan television and radio personality who lives in Auckland.

“We are breathing and sleeping a little better,” he said.

The United Nations said about 84,000 people – more than 80 per cent of the island nation’s population – had been badly affected by the disaster.

“They have been affected through loss of houses, loss of communication, what we understand is the issue with the water,” UN spokesman Stephane Dujarric said.

The most pressing humanitarian needs are safe water, food and non-food items, he said.

“Water is really the biggest life-saving issue. Water sources have been polluted, water systems are down.”

Damage to trees and structures from the impact of the tsunami. Photo: Tonga EU Consulate

New Zealand said Tonga, one of the few countries to be free of the coronavirus, had agreed to receive two of its ships carrying aid and supply, despite concerns about importing an outbreak that would make matters worse.

The vaccination rate is as high as 90 per cent among Tongans.

The ships, which are carrying 250,000 litres of water along with other supplies, will arrive on Friday.

HMAS Adelaide was expected to depart Brisbane on Wednesday, carrying more aid.

The Hunga Tonga-Hunga Ha’apai volcano erupted about 65 kilometres from the Tongan capital with a blast heard 2300 kilometres away in New Zealand, and sent tsunamis across the Pacific Ocean.

Waves reaching up to 15 metres hit the outer Ha’apia island group, destroying all the houses on the island of Mango, as well as the west coast of Tonga’s main island, Tongatapu, where 56 houses were destroyed or seriously damaged, the prime minister’s office said.

The UN said evacuation of people from these islands was under way.

The UN hoped the country’s airport would be operational on Thursday.

-with AAP