The death toll from Vanuatu's devastating cyclone was revised down to 11 on Monday, according to the United Nations which also said contributions to the South Pacific nation's recovery have topped US$10 million.

The United Nations Office for the Coordination of Humanitarian Affairs (OCHA) had on the weekend put the number of fatalities at 16, but its latest update noted that the Vanuatu government had advised the number was 11.

Dozens were initially feared dead from the maximum category-five cyclone, with early reports from OCHA giving an unconfirmed 44 dead.

Its official figure has been revised several times since, climbing as high as 24 before settling at 11 on Monday.

Severe Tropical Cyclone Pam, which hit Vanuatu on March 13, bringing sustained winds of more than 250 kilometres (155 miles) per hour, has affected some 166,600 people on 22 of the nation's 80-plus islands.

"Initial assessment reports confirm destruction ranging from 20 to 90 percent of houses, schools, clinics, churches and crops on all 22 affected islands," OCHA said.

Lack of shelter remained a key factor, while residents had only limited access to safe water and food stocks were running low.

OCHA said as of Sunday, its financial tracking service had recorded a total of US$10 million in contributions from foreign donors, including Australia, Britain, New Zealand and the European Commission.

Australia's Foreign Minister Julie Bishop, who made a flying visit to Vanuatu on Sunday, said that Canberra would assist its Pacific neighbour for the long term.

"We will continue to work closely with the (Vanuatu) government as it begins the long road to recovery," Bishop told the ABC on Sunday.