Australian navy ship HMAS Adelaide has docked in Tonga to deliver humanitarian supplies despite nearly two dozen personnel onboard testing positive to COVID-19.

Australia joined several other countries in sending crucial supplies to Tonga after a volcanic eruption and tsunami earlier this month, but its delivery became uncertain on Tuesday when 23 people on board the navy ship tested positive for the virus.

Tonga is currently COVID-free and has insisted that foreign aid donors deliver supplies without any person-to-person contact to prevent potential transmission.

After liaising with Tongan authorities, the ship was granted permission to dock and has since offloaded humanitarian and medical supplies, along with engineering equipment and helicopters.

In a statement, Foreign Minister Marise Payne said the delivery was entirely contactless to avoid transmission. 

Tonga's health minister, Saia Piukala, told Broadcom Broadcasting radio that the HMAS Adelaide would begin its return journey to Australia after delivering the supplies.

"The ship will berth and no contacts will be made … Australians from the ship will unload their cargoes and sail from port," he said.

Australia has supplied more than 40 tonnes of emergency relief to Tonga since the January 15 disaster and will provide an extra $2 million in funding to help the island nation recover.

The federal government said Australia would also broaden its support by helping restore power and communications across the country.

Humanitarian aid to the Pacific Island nation is expected to ramp up after the airport was cleared of ash, making it safe for planes to land.

The International Federation of Red Cross and Red Crescent Societies (IFRC) said that with the extra supplies, its staff and volunteers were increasing deliveries of drinking water and setting up shelters across the country's islands.

"This disaster has shaken the people of Tonga like nothing we have seen in our lifetime," Sione Taumoefolau, secretary-general of Tonga Red Cross, said in a statement.

"The tsunami has wiped out homes and villages, but we are already rebuilding amid the ashes."

Tonga has been reeling from the impact of an undersea volcanic eruption on Hunga Tonga-Hunga Ha'apai, around 65 kilometres north of Tonga's capital Nuku'alofa, which triggered a tsunami with up to 15-metre-high waves. 

The eruption and tsunami killed three people, destroyed villages and resorts and severed communications to the island with a population of around 105,000 people.

The disaster also severed the country's undersea communications cable. However, a cable company official expects the main island's internet service to be restored within two weeks.

Tonga's Digicel phone network has been able to restore international call services to some areas via satellite connections, and some people have been able to send emails or get limited internet connectivity.

Tonga Cable chairman Samieula Fonua said preliminary estimates indicated the break in the undersea cable was located about 37 kilometres off the main island of Tongatapu.

He said the cable should be repaired by February 8, restoring the internet to about 80 per cent of Tonga's customers.

Mr Fonua said the focus was on fixing the main international cable, with domestic connections to be dealt with "at a later time."

He said Tongans had been largely understanding of the communication disruptions caused by the disaster.

"People are calm. Coming out of a total blackout, just being able to call outside and send an email has settled them a bit," Mr Fonua said.

"By the time they start getting more frustrated, I'm hoping we'll have the cable connected by then."

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