Aid is slowly making its way through Vanuatu in the aftermath of devastating Cyclone Pam, as Australia ups its relief effort with troops and two Army Black Hawk helicopters.

The Category 5 storm barrelled into the South Pacific island nation a week ago, bringing sustained 250-kilometre per hour winds and devastating entire communities.

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Aid packages – including medical, hygiene and food kits – were being loaded onto barges in the capital Port Vila destined for the nation’s southern province and outlying Shepherd Islands, Vanuatu Disaster Management co-ordinator Augustine Garae told AAP on Saturday.

“We have logistics on the ground from the Red Cross,” Mr Garae said.

Vanuatu Prime Minister Joe Natuman. Photo: ABC

“We’ve started distributing relief supplies to Tanna Island and we’re loading some onto a barge to distribute to the vulnerable Shepherd island tonight.”

But he said the supplies weren’t limitless.

“We need more support in terms of relief items. We will need more support.”

Defence Minister Kevin Andrews said the Blackhawks would be sent to Vanuatu aboard an RAAF C-17 transport aircraft.

There are now 78 defence personnel on the ground in Vanuatu, with another 335 expected early next week aboard transport ship HMAS Tobruk.

More than 166,000 people – half of Vanuatu’s population – has been affected by Pam, the UN’s Office for the Coordination of Humanitarian Affairs said in a situation report.

The agency said the confirmed death toll had risen to 16, as aid workers were able to reach new areas, with completed assessments covering 15 islands.

Aid agencies stress potable water, food, shelter and health are a priority in the aftermath of the storm which hit late on March 13.

The latest assessment found damage to food crops has been extensive.

In some areas local residents would not only lose their main source of income but their food security would be threatened by loss of livestock, it said.

In its situation report, OCHA said access to some communities was still hindered across the sprawling nation which is made up of more than 80 islands.

But it said between 50 and 90 per cent of dwellings were estimated to have been damaged by the fierce winds which pounded Vanuatu as the eye of the storm hovered over the nation for hours, leaving 65,000 people in need of emergency shelter.

The agency said fuel stocks were running low across affected islands while electricity was mostly unavailable.