Three people in Tonga were killed by the January 15 tsunami, dozens of homes destroyed and drinking water was tainted.

The fibre-optic cable is fully operational again after being reconnected on Tuesday, said Samiuela Fonua, chairman at Tonga Cable Ltd., the state-owned company that owns the cable.

"It's a huge relief when you know things have come to the end and are working well," Fonua told The Associated Press.

"It's one step forward for the country."

Fonua said the crew aboard a repair ship replaced about 90 kilometres of cable that had been damaged by the tsunami. His company didn't have enough spare cable, Fonua added, and needed to borrow some from other companies.

The fix means that Tonga Cable can now focus on repairing a second severed cable that connects some of the outer islands to the main island, Fonua said. That cable runs close to the undersea volcano.

Fonua said that entrepreneur Elon Musk's SpaceX company had also been helping restore connections through its network of low-orbit satellites called Starlink.

Fonua said his company had been testing the satellite connections this week and they had been working well and that now the main cable was restored, he hoped the SpaceX connections could be used for reconnecting people on some of the outer islands.

Officials in neighbouring Fiji said SpaceX had established a station there to help restore connections in Tonga.

Tonga has also been grappling with its first outbreak of COVID-19, which may have been brought in by foreign military crews aboard ships and planes delivering vital aid after the eruption.

The outbreak has grown to more than 250 cases but so far there have been no reported deaths. The country of 105,000 has begun easing some restrictions after initially imposing a lockdown.

Tongan health officials say that 90 per cent of people aged 12 and over have had at least two vaccine doses.

Australian Associated Press