The man's story is reminiscent of the 2000 film starring Tom Hanks

A castaway who washed up on the Marshall Islands in the Pacific Ocean has claimed he has survived the past 16 months adrift at sea.

The emaciated man, who was discovered with long hair and a beard and dressed only in a pair of underpants on a remote Pacific atoll, said he survived by eating turtles, birds and fish and by drinking turtle's blood when there was no rainwater.

The man, who speaks only Spanish, says he left Mexico for El Salvador in September 2012 with a companion, who died several months ago. He claimed he survived on their 24-ft fibreglass boat for 16 months by catching his food with his bare hands as there was no fishing gear.

He was found more than 8,000 miles away from his setting-off point on tiny Ebon Atol.

"His condition isn't good, but he's getting better," Ola Fjeldstad, a Norwegian anthropology student doing research on Ebon, said.

"The boat is really scratched up and looks like it has been in the water for a long time."

The locals who found the man took him to the main island, Majuro. The mayor took up his case and phoned the Ministry of Foreign Affairs.

"He's staying at the local council house and a family is feeding him," said Fjeldstad. The mystery man did not appear to have any life-threatening illnesses, but did have low blood pressure.

"We've been giving him a lot of water, and he's gaining strength," she added.