Tongans said they were determined to rebuild their battered homeland in the wake of last week's devastating eruption and tsunami as a massive clean up continued Saturday in the Pacific kingdom.

The powerful eruption of the Hunga Tonga-Hunga Ha'apai volcano last Saturday triggered a tsunami that crashed across the Tongan archipelago, affecting more than 80 percent of the population, according to the United Nations.

Toxic ash polluted drinking water supplies, crops were destroyed and at least two villages have been completely wiped out.

Delivering humanitarian supplies remains a challenge after the undersea cables connecting Tonga to the rest of the world were severed.

But Tongan journalist Marian Kupu said most locals are adamant on remaining as the huge recovery efforts began.

"We want to stay here in our country because this is what identifies us as Tongans. We want to rebuild our country and unite and move on," Kupu told AFP.

An estimated one cubic kilometre of material blasted from the volcano, and experts expect Hunga Tonga-Hunga Ha'apai to remain active "for weeks to months".

"Tonga's people are going to need sustained support responding to a disaster of this scale," Sione Hufanga, the United Nations Coordination Specialist in Tonga said.

"The people of Tonga are still overwhelmed with the magnitude of the disaster."

Tonga ranks third on the World Risk Report, which measures countries on their susceptibility to experiencing natural disasters.

Despite the risk, Kupu said most Tongans wanted to stay.

"It's this feeling of pride that we have here, that we don't want to leave the country we were born and raised in," she said.

One survivor from the island of Atata, which was flattened by the tsunami, told her he would return to the island even after the devastation, she added.

A handout photo taken on January 18, 2022 and released on January 21 by New Zealand Defence Public Affairs shows an aerial view of Mango Island following the eruption of the Hunga Tonga-Hunga Ha’apai undersea volcano on a nearby island on January 15.
A handout photo taken on January 18, 2022 and released on January 21 by New Zealand Defence Public Affairs shows an aerial view of Mango Island following the eruption of the Hunga Tonga-Hunga Ha’apai undersea volcano on a nearby island on January 15. Defence Public Affairs via AFP / Handout

"He explained he wished to go back because his parents are buried there, he was born there and his life is there.

"He wished the government or anybody would help rebuild his little island so he could go back."

Japanese, New Zealand and Australian defence forces have started delivering urgent relief supplies, particularly water, to Tonga but an Australian minister said fears of unleashing a "Covid crisis" were complicating aid efforts.

Tonga is Covid-free and has strict border control policies, requiring contactless delivery of aid, and a three week quarantine period for any humanitarian personnel who wish to enter the country.

"It's a very, very difficult time for the people of Tonga," Australia's international development minister Zed Seselja said, but added: "We respect absolutely the desire of the Tongan government not to add a Covid crisis to a humanitarian crisis caused by a tsunami."

On Saturday, a Japanese plane brought potable water to the kingdom, Kyodo News reported, with three other aircraft and a transport vessel carrying high-pressure cleaners expected soon.

Meanwhile, a third New Zealand navy vessel carrying helicopters, water, tarpaulins, milk powder and engineering equipment is on its way to Tonga and is expected early next week.

Defence Minister Peeni Henare said all deliveries will be contactless in accordance with Tonga's Covid-19 protocols.

The Tongan government has called the dual eruption-tsunami "an unprecedented disaster" and declared a nearly one-month national emergency.

The eruption broke a vital undersea communications cable, and it is expected to be at least a month before all communication services are fully restored.

In the meantime, partial communications has been established, although mobile network provider Digicel said the high number of calls to the island was producing delays.