Pacific castaway Jose Salvador Alvarenga has been ordered to rest after being hospitalised with a health scare, as a senior diplomat said all evidence so far verified his amazing story.

A castaway who says he survived 13 months adrift in the Pacific said he thought about suicide but was sustained by dreams of eating his favourite food — tortillas — and reuniting with his family.

An emaciated man whose boat washed up on a remote Pacific atoll this week claims he survived 16 months adrift, floating more than 12,500km from Mexico, a researcher said.