Christmas Island administrator Jon Stanhope said despite the men not being Australian citizens, they were responsible for ''inordinately brave'' acts in Australian waters and their courage should be commended.

In January, authorities rescued about 16 asylum seekers on a boat foundering 20 nautical miles from Christmas Island.

Those on board told rescuers that the day before, the three men from Myanmar and an Indonesian crewman had built a makeshift raft by lashing inner tubes and bamboo together, and had set out to get help.

After four days the crewman washed up alive on Christmas Island, badly sunburnt and dehydrated. The bodies of the three Myanmarese were never found.

''Christmas Island, a tiny speck in the Indian Ocean, wasn't visible,'' Mr Stanhope told ABC radio on Monday.

''I think that's an act of just unimaginable bravery. Fifteen nautical miles at sea [on] an inflatable automobile tyre and to begin to paddle … I believe they deserve the highest bravery award,'' he said.

He says he had advice from the Australian Honours and Awards Secretariat that the men were eligible to receive bravery awards because the acts took place in Australian territory.

Meanwhile, confusion still surrounds the fate of one - and possibly two - boats believed to have sunk in Indonesia's Sunda Strait last week, en route to Christmas Island.

Indonesia is yet to launch an aerial search for scores of missing asylum seekers amid fears two boats bound for Australia may have gone down in recent days.

Initial reports from the Australian Maritime Safety Authority suggested an asylum-seeker boat sank early on Friday, and that some survivors were possibly rescued by fishermen.

But one survivor says he was on a vessel which sank on Wednesday, and he was rescued on Thursday after spending 24 hours in the water, raising fears there may have been another vessel.

with AAP

Follow the National Times on Twitter