SCEPTICISM mounted yesterday over claims by two Burmese that they had floated for 25 days inside an industrial-sized esky after their fishing boat sank in the Indian Ocean.

The two men, aged 22 and 24, rescued on Saturday, emerged yesterday from hospital on Thursday Island with few physical signs of their ordeal.

Medical staff expressed surprise at their remarkably good condition, given the 30C-plus days and Cyclone Charlotte-generated rough weather while they were adrift.

Queensland Heath spokesman Jim Guthrie said the men were "in a good condition" when they were discharged.

With their only water collected from the bottom of their unlikely liferaft, the men suffered little more than a few abrasions and dehydration.

"Doctors have reported that they are in remarkable condition, given their claimed exposure to the elements for almost a month," a source told The Australian.

"There is no sunburn, no chafed lips, no discernible signs that the men were out there that long."

An Immigration Department spokesman said the men had been taken to nearby Horn Island, where they were being interviewed and held in a motel for several days.

"I think it will take several days to get to the facts and get to the bottom of their claims."

Unless the men claim refugee status, they would normally be treated as "survivors, lost at sea" and returned to their home within weeks. But the Immigration spokesman said it was too early to report on the men's intentions or bona fides.

The men, who were not carrying any identification, have told authorities that they were indentured workers, forced to work aboard the Thai fishing vessel.

They say their 18 fellow crew members died at sea and did not have any flotation devices when their boat sank in a squall southeast of Indonesia.

A spokesman for the Australian Maritime Authority said a search-and-rescue mission was not launched for the rest of crew, after Saturday's rescue because the two men had been unable to provide information on where the 10m vessel had sunk.