The aircraft, from Chivenor in north Devon, was flying the men to Brest in northern France.

The helicopter first lowered a pump to the Spanish vessel Mareton, which asked for help after taking on water about 160 miles west of the Isles of Scilly.

Six other crew members stayed on board, and a second helicopter from the Royal Navy was standing by at the scene.

The second aircraft was sent from Royal Naval Air Station Culdrose in west Cornwall.

A Spanish naval vessel was also standing by, said Falmouth coastguards.