A key undersea cable that was destroyed in a volcano eruption in Tonga may take at least four weeks to be repaired, say New Zealand officials.

The cable was severed during a volcanic eruption on Saturday, crippling communications and cutting the Pacific island off from the outside world.

The eruption also caused a tsunami, which left houses devastated and three dead – including a British national.

Teams have been working round the clock to to get vital supplies to the region.

“US cable company SubCom advises it will take at least four weeks for Tonga’s cable connection to be repaired,” a statement by New Zealand’s foreign affairs ministry said on Wednesday.

Tonga has been unable to establish external contact since Saturday’s violent eruption severed the country’s only underwater sea cable in two places.

Scant communication has been established since then, enabled through a few satellite phones mainly held by foreign embassies in the capital city Nuku’alofa. Many Tongans abroad have since been waiting to hear news from loved ones.

Telecommunications firm Digicel is expected to set up an interim 2G connection today that prioritises voice and SMS communications, the statement added.

This is not the first time Tonga’s only undersea cable has been damaged. A bout of bad weather inflicted unexpected damage on the cable, causing a near total blackout of mobile and internet services for the 100,000 residents in the island nation.

The eruption – described by the Tongan government as an “unprecedented disaster” – caused wide swathes of Tonga to be blanketed in thick ash, hampering relief planes from landing and delivering much-needed food and drinking water.

New Zealand authorities say the Tonga’s main airport runway is expected to be cleared today, after rescue teams and volunteers desperately worked to clear ash from the tarmac using wheelbarrows and shovels.

On Wednesday morning in Tonga, a UN representative for the region said that while clearing the ash on the main island of Tongatapu had proven more difficult than expected, good progress had been made and it was hoped that flights might soon resume.

“We thought that it would be operational [Tuesday], but it hasn’t been fully cleared yet because more ash has been falling,” Jonathan Veitch told reporters.

Mr Veitch praised the quick response of New Zealand and Australia in working to dispatch aid via navy ships, which he said had the ability to desalinate sea water and provide fresh supplies for the local population.

The Tonga Government has approved the arrival of the HMNZS Wellington and HMNZS Aotearoa, which departed New Zealand yesterday, as well as a C130 Hercules plane once the airport runway is clear.

They are expected to arrive in Tonga by Friday, depending on weather conditions.

Mr Veitch said the vessels were carrying “a lot of our water and sanitation supplies” and described a “very challenging” situation on the islands. The vessels are believed to be the first shipment of international supplies to reach Tonga.

Tongan officials have also expressed concern that deliveries could spread Covid, with the country only recording its first case in October.

The UN said it was unclear if personnel could be sent to assist, but that supplies like water and food could be delivered as the main island’s port remained viable.

There have been reports of food supplies at shops running low and deliveries have been deemed a priority.

Saturday’s volcanic eruption was felt as far away as the US. In Peru, two people drowned in abnormally high waves while beaches near the capital Lima were closed off following an oil spill.