International aid agencies are preparing to begin emergency helicopter flights on Tuesday to the remote outer islands of Vanuatu, which they fear have been devastated by a monster cyclone that tore through the South Pacific island country.

Disaster management officials and relief workers are still struggling to establish contact with the islands that bore the brunt of Cyclone Pam's winds of more than 300 kph (185 mph) on Friday and Saturday.

The cyclone killed at least 24 people and left some 3,300 people homeless after it destroyed homes, flattened buildings and washed away roads. Officials anticipate that number will rise once they are able to land on the outer islands of the scattered archipelago to inspect the damage there.

"We have no contact of any sort with the outer islands, the priority is to get communications up and running. It's very, very concerning that we haven't heard anything from the outlying islands," Joe Lowry, a spokesman for International Organisation for Migration (ILM), told Reuters in Port Vila.

"If the devastation is as high as we think it is on those islands, there is a chance that the death toll will go up very significantly."

Aid agencies and rescue teams from Australia and New Zealand have flown over the islands, but have so far been unable to land because of flooding. The helicopters will be able to land on higher ground, giving rescue workers a clearer picture of the overall impact.

The Australian Red Cross said it had reports of "total devastation" on the southern island of Tanna, with most homes destroyed and at least two people dead. Tanna, about 200 km (125 miles) south of the capital with its 29,000 inhabitants took the full force of the category 5 storm.

Reports from aid groups also said the main town on the island of Erromango, north ofTanna, had suffered similar destruction.

In Port Vila, the clean-up was beginning, but there were worries about starvation after the main local food market was destroyed.

The majority of locals rely on foods sold at the downtown market such as taro, island cabbage, bananas, kumala and yams for their staple diet.

Shops selling tinned food were open and stocked in the capital, but most locals do not have the money to buy those foods and many were reported scavenging for bananas or fruit.

"We have bread for the first time today because the bakery has opened," said shop owner Colette Calvo.

"We have water but the situation is very bad because people don't have local food," Calvo added. "All they can eat is food like bananas that they pick up off the ground and they can get sick."

Red Cross Vanuatu CEO Jacqueline de Gaillarde said shops were already low on supplies because people had stockpiled food before the storm but those supplies were then lost when homes were destroyed.

Diseases, including dengue fever and malaria, were a concern amid widespread flooding, she added.

Central Port Vila was relatively unscathed with most of the concrete buildings still standing, but as much of three-quarters of the capital's houses were reported destroyed or severely damaged after seas surged as high as 8 metres (26 feet).

Long queues formed at petrol stations, with many people lining up for hours.

A 6 p.m. to 6 a.m. curfew had been imposed in the capital to prevent looting, said Colin Collett van Rooyen, Oxfam's country manager.

Aid arriving

Formerly known as the New Hebrides, Vanuatu is a sprawling cluster of more than 80 islands and 260,000 people, 2,000 km (1,250 miles) northeast of the Australian city of Brisbane.

Perched on the geologically active "Ring of Fire," one of the world's poorest nations suffers from frequent earthquakes and tsunamis and has several active volcanoes, in addition to threats from storms and rising sea levels.

Military flights from New Zealand and Australia were bringing in water, sanitation kits, medicines and temporary shelters for the estimated 10,000 made homeless on the main island, with supplies being unloaded late into Monday evening at the airport. France and the United States were also sending aid.

Commercial flights resumed on Monday, bringing in more aid and evacuating tourists.

President Baldwin Lonsdale, who had been in Japan for a United Nations disaster conference when the storm hit, said it would take time for his country to recover.

"What is happening now is that, as I've seen over and over again, the people of the republic of Vanuatu need humanitarian assistance at the moment," he said. "And I'm very pleased with the international community that they have responded to my appeal."

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.