Outlying areas of Vanuatu suffered significantly worse damage than capital Port Vila after the South Pacific archipelago was hit by Cyclone Pam over the weekend, aid workers have reported.

Teams carrying medical supplies, food, water and shelter equipment landed on the outer islands of Tanna and Erromango, agencies said.

Getting aid to the islands has proven difficult because of a lack of landing strips or deepwater ports.

Eleven people have died, the UN said, revising down an earlier toll of 24.

Tanna island has a population of about 30,000 people and is about 125 miles south of the capital Port Vila. It was directly in the path of the cyclone.

Tom Perry from Care Australia said relief workers in Tanna reported the hospital was functioning but had no roof.

“The impression they got from their initial observations was that the damage is significantly worse than Port Vila,” Tom Perry told AFP news agency.

Australian Foreign Minister Julie Bishop said military planes flown over the islands had reported major damage to houses and crops.

“We understand that the reconnaissance imagery shows widespread devastation,” Julie Bishop said of Tanna.

“Not only buildings flattened – palm plantations, trees. It’s quite a devastating sight.”

Communication to many of the other 80 islands in the archipelago are still down and officials have warned survivors could quickly run out of food.

Aurelia Balpe, head of the International Federation of Red Cross and Red Crescent Societies (IFRC) for the Pacific, says the Vanuatu government is coordinating assessment and aid, including flights to other islands.

Aid agencies have organized themselves in clusters to better co-ordinate help, but getting to islands is not easy.

“There are difficulties in understanding how large a plane can land on some islands. In many of these small islands, they don’t have ports that can handle large vessels. In some places we may need to construct landing places for planes and boats,” she said.

Many smaller boats in Port Vila were damaged by the storm, and the distance is a challenge.

“It’s about 150km from Port Vila to the island of Erromango – which would take at least four hours in a small boat – and another 80km from Erromango to Tanna,” Aurelia Balpe said.

Poor weather and rough seas are also an issue.

“The first couple of days were very difficult because of the cyclone, and even now there are really bad swells and storm surges,” Aurelia Balpe said.

Cyclone Pam, a category five tropical storm, hit Vanuatu on March 14, bringing very high winds.

Across the Pacific nation, many people have lost their homes or face extensive rebuilding. Telecommunications, power and water supplies have all been badly affected.

In Port Vila a clean-up is under way but the destruction was extensive. Power and water have been restored in some areas but up to 90% of homes have been damaged.

The hospital is coping with an influx of injured people but a surgeon said beds had been moved outside because of structural damage.

On the main island and in the provinces of Torba and Penama to the north, some 3,300 people were in evacuation shelters, the UN Office for the Coordination of Humanitarian Affairs said.

Vanuatu’s President Baldwin Lonsdale, returning from a conference in Japan, has described the storm as a “monster” that wiped out years of development.

He has linked the disaster to climate change, citing changing weather patterns, rising seas and heavier-than-average rain in Vanuatu.

Australia announced on March 17 that it was sending more personnel, including a search and rescue team, and three more military planes carrying aid.

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