Four Indonesian fishermen who spent eight days adrift in the remote Timor Sea on a makeshift raft were rescued by marine authorities and a fishing vessel Wednesday, Australian officials said, adding that they were in "good health" despite their ordeal.

The men were spotted by an Australian Border Force plane in the Timor Sea on Tuesday evening and a nearby fishing vessel AFV Exodus was called on to pick up the men early Wednesday morning, the Australian Maritime Safety Authority (AMSA) said.

The fishing boat was later met by the Australian Navy ship HMAS Maitland, AMSA added.

"All survivors have been medically assessed and are in good health. The fishermen will be repatriated to their home port of Kupang, Indonesia," AMSA said in a statement.

The skipper of the Exodus, Gary Finlay, said the men were "140 miles off the nearest Kimberley Coast... basically in the middle of nowhere".

"It was a wing and a prayer keeping them afloat," Finlay told the Australian Broadcasting Corporation, adding that the raft was just 1.5-square-metres (16-square-feet) in size and made from debris from the fishermen's ship.

"They had two fuel cells latched together as the base of the boat then around the two fuel cells they had plastic 20-litre (5.3 US gallon) drums," he said.

"They had a couple of 40-litre plastic blue containers latched there and a 400-kilo (882 pound) ice box that was half submerged."

Finlay said when his crew found the Indonesians, they were knee-deep in water and their feet were "suffering".

But while they were hungry and "in a bit of shock", they were otherwise physically well, he added.