Survivors of Cyclone Pam in Vanuatu are facing long term food shortages because of damage to crops.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) has said at least 11 people were killed and thousands displaced when the cyclone hit the group of islands.

Aid agencies are warning those numbers could rise as communications are restored on each island.

CEO of communications company Digicel Pacific, which operates in the region, is Michael Murphy. He says they are working round the clock to get telecommunications back up and running:

Damage to a communications tower after Cyclone Pam

Formerly known as the New Hebrides, Vanuatu is made up of 83 islands and 260,000 people, lying around 2,000 kilometres northeast of the Australian city of Brisbane.

It is among the world's poorest countries and is vulnerable to natural disasters including earthquakes, tsunamis and storms.

Aid officials said the storm was comparable in strength to Typhoon Haiyan, which hit the Philippines in 2013 and killed more than 6,000 people.

President Baldwin Lonsdale, who happened to be at a disaster risk conference in Japan when the cyclone hit, compared the storm to a monster.

He said most houses in the capital Port Vila had been damaged or destroyed.

President Lonsdale said the impact would be "the very, very, very worst" in isolated outer islands but he held out hope the number of casualties would be "minor".