Tonga will enter a lockdown after finding coronavirus infections in two port workers helping distribute aid arriving in the Pacific nation following a volcanic eruption and tsunami.

All of the aid deliveries were to be handled using strict
All of the aid deliveries were to be handled using strict "no-contact" protocols in a bid to keep the virus at bay. (AP)

Tonga has said it will close its borders after Covid-19 was detected in the previously virus-free Pacific kingdom as it struggles to recover from last month's deadly disaster.

Prime Minister Siaosi Sovaleni said late on Tuesday that two men tested positive this week in the capital Nuku'alofa and were in isolation.

He said the men had been working in the city's port, where humanitarian aid has been pouring in from around the globe since the January 15 eruption.

"The most important issue at the moment is to slow down and stop those who have been affected," Sovaleni said during a national address.

"That's the reason for our national lockdown... no boat will be allowed to go from one island to another, no more (domestic) aeroplane flights."

Sovaleni said Tonga would close its borders from 0500GMT on Wednesday, with the situation reviewed every 48 hours.

READ MORE: Tonga sees 'extensive damage' from volcanic eruption as evacuations begin

'No-contact' aid protocol

The volcanic blast, one of the biggest recorded in decades, generated massive tsunami waves and blanketed the island nation in toxic ash, claiming three lives.

In response, Australia, New Zealand, the United States, China, France, Fiji and Britain have sent ships carrying aid including drinking water, medical supplies and engineering equipment.

All of the deliveries were to be handled using strict "no-contact" protocols in a bid to keep the virus at bay, including leaving goods in isolation for three days before they are handled by Tongans.

Sovaleni did not reveal which ship the affected men had been working with.

He said they were asymptomatic and double vaccinated, along with about 85 percent of Tonga's population.

Australia's HMAS Adelaide docked in Nuku'alofa to unload supplies last week, despite a coronavirus outbreak that infected more than 20 of its crew.

The Australian Defence Force did not respond to a request Wednesday for the ship's latest coronavirus numbers, but Australian broadcaster ABC reported cases had soared to more than 70.

A United Nations update late last week said drinking water remained Tonga's main challenge and about 1,500 people were still displaced.

READ MORE: Tonga volcanic eruption highlights risk to global telecoms network

Source: TRTWorld and agencies