A survivor of a plane crash described yesterday how he and four other passengers survived a six-hour swim to safety in stormy waters after holding a prayer session.

Pastor Neil Watts also told of his anguish as he was forced to leave an English anthropologist who fell behind on the swim from the plane wreck in the South Seas.

Dr Andrew Gray, an anthropologist from Oxfordshire, escaped from the wreckage of the Twin-Otter aircraft after it plunged into the ocean.

He was slightly injured and has not been seen since.

Six other people died when the Van Air plane crashed during a planned one-hour flight from the island of Espiritu Santo to Port-Vila, the capital of Vanuatu, on the island of Efate.

Five passengers survived the accident and reached land after the six-hour swim.

Pastor Watts, one of the Australian survivors of the crash, described his ordeal and relived the moments when he lost sight of Dr Gray in the rough seas.

Pastor Watts, a Seventh Day Adventist, said: ''Suddenly the engines were cut and within a second or two there was a sickening crash and we all jolted forward and the plane immediately began to fill with water.''

He said he, Dr Nicole Leeks and Royal Australian Air Force Flight Lieutenant Tim Hurford, who are both from Perth, Australia, plus a Danish man and a man from Vanuatu managed to swim to safety.

Dr Gray was with the group when they started swimming from the crash scene, but slowly fell back until they lost sight of him.

Pastor Watts said that once the survivors were out of the plane, he rallied the group of six for a prayer session and then began swimming for the distant lights of Port-Vila.

Only two of the six found lifejackets.

''As soon as we got out of the plane it sunk and everything was quiet and dark and we could see how far away land was, we knew we were in trouble,'' he said.

His group swam slowly for about 90 minutes, when the Englishman began to fall behind.

''He began to drift further and further and we could hardly see each other,'' Pastor Watts said.

''The waves came up a little bit ...and eventually he was too far away and we couldn't see where he was and he drifted off.''

After four hours fighting the current, the survivors decided to head for a light on an outcrop, rather than Port-Vila, he said.

They briefly rested by grabbing hold of a boat anchor chain several hundred yards off shore, before reaching the beach, collapsing and praying.

The survivors made it to the light they had seen, the home of a man who gave them hot drinks and blankets and telephoned police.

''We were just so happy to be alive,'' Pastor Watts said.

The Republic of Vanuatu, formerly the New Hebrides, is an archipelago of 82 islands strung across 812 miles of the Pacific about 625 miles west of Fiji.

Mr Arthur Caulton, police chief of staff in Port-Vila, confirmed passengers, including Dr Gray, escaped from the aircraft as it sank, and started swimming.

He said rescue workers would continue the search for Dr Gray, 43, and six other passengers, two French and four Vanuatu nationals.

However, almost two days after the accident, the chances of finding any survivors were very remote.

Dr Gray's older brother, Mr Richard Gray, said the family had been waiting desperately for news since they were informed about the crash on Sunday morning.

He said: ''We have heard that he still hasn't been found and that was a few hours ago.

''It is very difficult not knowing. We are not very optimistic at all now. It has been such a long time.''

He was comforting Dr Gray's wife Sheila at her home in Headington, Oxfordshire.

Mr Gray, from Lewes, Sussex, said Sheila was in regular contact with the wife of one of the survivors, who is based in Copenhagen.

He said his brother had been travelling with a colleague who had survived the crash.

Dr Gray went to the South Pacific a couple of weeks ago to work with an organisation involved with indigenous people throughout the world.

He had been due to travel on to Papua New Guinea in the next few days. His wife, who also works in anthropology, did not wish to comment on his disappearance.

The couple's 17-year-old son Robbie was at school yesterday .

The family has requested that their privacy be respected.

The five surviving passengers were recovering in Port-Vila after the gruelling six-hour swim to reach land.

Police chief Caulton said: ''The five survivors were extremely lucky because not only is it very hard to get out of a plane when it is submerged, but the distance they swam is unbelievable, especially in the dark and during a storm.''

He said they were taken to hospital to be treated for minor injuries.

He added: ''There was a very, very bad storm that night, but it is not yet clear exactly what caused the crash. The last accident of this kind was in 1989 when 12 people died. It is like history is repeating itself 10 years on.''

A spokesman for the Prime Minister's Office in Port Vila said a search would continue with the help of France and New Caledonia.

Helicopters and search planes were being used to scour the area for survivors, and to look for the wreckage of the aircraft.

Divers are expected to be sent in today to explore the area where the plane went down.

The spokesman confirmed that the teams were also looking for a ship which has been missing since Friday.

It is thought 25 people were aboard the small vessel, which was travelling between Efate and neighbouring island Emae.

He said: ''The ship went missing in bad weather on Friday. We have had very, very bad weather for the last couple of weeks.''