WELLINGTON — A deadly cyclone bearing down on the Pacific nation of Vanuatu has intensified into a Category Five super storm, generating destructive winds and "phenomenal" seas, forecasters said on Monday.

Tropical cyclone Harold, which claimed 27 lives when it swept through the Solomon Islands last week, strengthened overnight Sunday as it moved east, Vanuatu's meteorology service said.

It said the cyclone was now packing winds of up to 235 kilometres per hour, prompting red alerts in the provinces of Sanma, Torba, Penama and Malampa.

Officials warned residents in the nation of 300,000 to expect flash flooding and said ships should stay in port or risk facing huge swells on the high seas.

Harold is forecast to pass north of the capital Port Vila early Tuesday.

An inter-island ferry in the Solomons Islands ignored weather warnings as cyclone Harold was gathering strength late last week and 27 people were washed off its decks into the sea.

Solomons police said late Sunday that the bodies of five passengers from the MV Taimareho had been recovered and the search would resume the next day.

"I would like to thank everyone who have been involved in the search for the missing 27 people so far as we try as much as possible to find the bodies so their grieving relatives can give them a proper burial," chief superintendent Richard Menapi said.

The ferry set off from Honiara for Malaita island on Thursday night packed with more than 700 people as part of a government evacuation programme in response to the coronavirus crisis.

Vanuatu is still recovering from the last time a scale-topping, Category-Five system, Cyclone Pam, hit the impoverished Pacific nation in 2015.

It flattened Port Vila, killed 11 people and left a swathe of destruction that the World Bank estimated wiped out almost two-thirds of Vanuatu's economic capacity.

The disaster prompted a massive aid operation but aid agencies have expressed concerns a similar response will be hampered by a state of emergency imposed in a bid to keep COVID-19 out of the country.

"There have been no confirmed cases of COVID-19 in Vanuatu, but a significant disaster at this time could present serious logistical challenges to delivering life-saving aid," Oxfam's Vanuatu director Elizabeth Faerua said.

The Solomon Islands and Vanuatu are among the few countries with no reported cases of the virus. — AFP