HMAS Manoora, an amphibious transport ship, was en route to Australia from the Persian Gulf when it was diverted to help the man, a spokesman said.

The unnamed fisherman, said to be in his mid 30s, was initially transferred from his vessel, Golden Sun, to a faster merchant vessel, the Claudia, to speed up the rendezvous with the Navy boat.

In rough conditions, Manoora's doctor and an assistant were transferred to the Claudia about 400-kilometres (248 miles) off the Western Australian coast.

A Navy spokesman said the man was paralysed from the waist down suffering from what appeared to be a viral or bacterial infection.

He was in a stable condition.

Claudia and HMAS Manoora were both en route to the port of Fremantle, which they were expected to reach about midday Saturday, the spokesman said.

This was the second time inside a month the Manoora has helped stricken seamen, Defence Department officials said.

It rescued eight merchant sailors from a sinking vessel in the Persian Gulf three weeks ago.

WAR.WIRE