Authorities said rescuers were working round the clock to reach six villages, currently inaccessible by road.

Rescuers in Indonesia are using drones and sniffer dogs to search for survivors after a powerful tsunami devastated the shorelines of the islands of Java and Sumatra and killed more than 400 people.

Military and volunteer teams on Tuesday deployed drones to assess the extent of the damage along the west coast of Java island, but torrential rains hampered rescue efforts.

Food, water, blankets and medical aid are trickling in to remote areas via inland roads choked with traffic.

Thousands of people are staying in tents and temporary shelters like mosques or schools, with dozens sleeping on the floor or in crowded public facilities.

Ayub, a 20-year-old fisherman sleeping with his family in a tent provided by the military, said the conditions in the camps were not ideal due to the rain, but that they had enough food.

“Everything is destroyed … My boat, motorcycle, house – all of it,” he told Reuters news agency. “The most important thing is we’re alive.”

Other residents of the same emergency camp, like Tarini, a mother of four, told Reuters their families had been left with nothing but the clothes on their backs.

“I’m sad for my children,” she said. “We want things to return to how they were, but we are afraid to return.”

At the nearby seaside town of Carita, which suffered some of the worst losses, local congregations held tearful Christmas vigils for victims.

While many churchgoers have fled the area for fear of further disasters, some like Nikson Sihombing came from temporary evacuation centres.

“We usually celebrate with joy and festivities, but with the tsunami, we can only pray humbly and not celebrate much for this year’s Christmas,” he said.

Devastating waves

Thick ash clouds continue to spew from Anak Krakatoa, a volcanic island where a crater collapse at high tide on Saturday sent waves smashing into coastal areas on both sides of the Sunda Strait between the islands of Sumatra and Java.

At least 154 people are still missing. More than 1,400 people were injured and thousands of residents had to move to higher ground, with a high tide warning extended to Wednesday.

Rescuers used heavy machinery, sniffer dogs and special cameras to detect and dig bodies out of mud and wreckage along a 100km stretch of Java’s west coast. Officials said the search area would be expanded further south, following the discovery of washed away bodies.

“There are several locations that we previously thought were not affected,” said Yusuf Latif, spokesman for the national search and rescue agency.

“But now we are reaching more remote areas…and in fact there are many victims there,” he added.

Authorities said rescuers were working round the clock to reach six villages, currently inaccessible by road and where waves from the tsunami were believed to be as high as five metres.

The meteorological and geophysics agency, BMKG, is asking residents to stay away from the shoreline by as much as 1km due to the risk of extreme weather on Wednesday and waves up to two metres high.

BMKG head Dwikorita Karnawati said on Tuesday the agency is worried about the rough weather making the volcano’s crater more fragile.

Experts warn that a second disaster remains possible.