AIRCRAFT carrying much-needed humanitarian supplies from Australia and New Zealand will arrive in tsunami-hit Tonga on Thursday, as the South Pacific island finally made contact with the rest of the world after being cut off for five days.

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

New Zealand's foreign minister said its air force has also sent a C-130 Hercules from Auckland, which will land in the Tongan capital Nuku'alofa at about 4 p.m. New Zealand time (0300 GMT).

"The aircraft is carrying humanitarian aid and disaster relief supplies, including water containers, kits for temporary shelters, generators, hygiene and family kits, and communications equipment," foreign minister Nanaia Mahuta said in a statement.

The delivery of supplies will be contactless and the aircraft is expected to be on the ground for up to 90 minutes before returning to New Zealand, she said. Tonga is COVID-19 free and is concerned that aid personnel may bring the virus.

The explosion of the Hunga Tonga-Hunga Ha'apai volcano on Saturday has killed at least three people, sent tsunami waves rolling across the archipelago, damaging villages, resorts and many buildings and knocking out communications for the nation of about 105,000 people.

Telephone links between Tonga and the outside world were reconnected late on Wednesday, though restoring full internet services was likely to take a month or more, according to the owner of the archipelago's sole subsea communications cable.

Speaking to Reuters from Nuku'alofa, journalist Marian Kupu said Tongans were cleaning up all the dust from the volcanic eruption but feared they may run out of drinking water.

"Each home has their own tanks of water supply but most of them are filled with dust so it's not safe for drinking," Kupu said.

A few villages on the Western side of Tonga were very badly hit, she said.

"I won't say we are expecting more deaths but as we are speaking the government is trying to fly to the other islands to check over them."

Asked if there were enough food supplies, she said: "I can say maybe we can survive for the next few weeks but I'm not sure about water."

'SIGH OF RELIEF'

New Zealand is sending two ships one of which is carrying 250,000 litres of water and desalination equipment that will be able to produce 70,000 litres a day.

It is due to arrive on Friday but the other New Zealand ship is due in on Thursday and will check shipping channels and wharf approaches at Tonga’s port.

Australia is also flying in desalination equipment, shelter, kitchens, and the sweeper to help clear the runway at the airport.

"There is obviously a lot of ash on the runway and a need to make sure that is it safe for some of the aid flights to land," Dutton told Australian radio.

Tongans abroad were frantically calling families back home to ensure they are safe.

"There's a sigh of relief as we are able to communicate with our loved-ones," said John Pulu, an Auckland-based Tongan television and radio personality.

"We are breathing and sleeping a little better."

The United Nations said that about 84,000 people – more than 80% of the population - has 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," U.N. spokesman Stephane Dujarric told reporters.

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

"Water is really the biggest life-saving issue."

The Hunga Tonga-Hunga Ha'apai volcano erupted about 40 miles (65 km) from the Tongan capital with a blast heard 2,300 km (1,400 miles) away in New Zealand.

Waves reaching up to 15 metres (49 feet) hit the outer Ha'apai 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.