Torrential rains and destructive winds continue as the storm moves slowly over land. (Photo: AP)
A deadly Pacific cyclone cut off communication links to Vanuatu's northern islands Tuesday, with aid officials saying they had grave concerns for residents in the remote areas.
Tropical Cyclone Harold, which claimed 27 lives when it swept through the Solomon Islands last week, lashed Vanuatu's northern provinces overnight as a scale-topping category five superstorm.
Red Cross Vanuatu secretary general Jacqueline de Gaillande said the cyclone, packing winds of up to 235 kilometres per hour (145 miles per hour), brought down buildings and caused flash flooding.
"We cannot say for certain what the damage is because communications are down," she said, adding that the most recent updates were social media posts from Monday evening.
"They showed a lot of damage but we have no numbers of casualties yet."
The last category-five storm to hit Vanuatu, Cyclone Pam in 2015, flattened Port Vila, killed 11 people and wiped out almost two-thirds of the country's economic capacity.
De Gaillande said Vila escaped the worst of Harold but she feared for those in areas further north that bore its brunt.
"I'm very concerned," she said.
"In Vanuatu homes are not built very strongly and I'm afraid there will be lots of people who have lost their belongings and do not have a place to stay."
De Gaillande said a complicating factor in relief efforts were travel restrictions imposed to help Vanuatu remain one of the world's few places with no confirmed COVID-19 cases.
Authorities in Port Vila have sealed off international borders and banned inter-island travel to minimise chances of the virus spreading.
De Gaillande said that meant aid agencies could not arrange domestic flights to cyclone-hit areas to carry out damage assessment and bring in supplies.
The 2015 cyclone sparked a major international relief effort but a similar operation now would run the risk of importing the virus to a country that lacks the health infrastructure to deal with even a mild outbreak.
Cyclone Harold has already caused widespread damage in the Solomon Islands, where an inter-island ferry ignored weather warnings and 27 people died after being washed off its decks.
Modelling early Tuesday showed it continuing to track southeast, passing south of Fiji as a category four Wednesday and weakening to category two as it brushes Tonga a day later.
However, the storm system has already proved unpredictable, with forecasters initially expecting it to only reach category three before petering out.
Fiji on Tuesday pre-emptively issued cyclone alerts for its southern islands, warning of high seas and damaging gale-force winds.