A dog has saved the life of a drowning man at Malaga Port in Spain.

The chocolate labrador, Nanook, was being walked nearby by his owner, Jose Ignacio, on Thursday.

Nanook began to bark unexpectedly and pull his owner towards the sea wall, The Local reported.

The behaviour was unusual, as Nanook is usually “very calm, well behaved and playful,” according to Mr Ignacio.

Nanook led him to a spot where a man, described as "thin and in his sixties" was flailing in the water, Euro Weekly News reports, but his calls for help were being drowned out by the sea.

(Undoubtably, the hero of the day [Nanook])

Mr Ignacio immediately went for assistance, and the man was rescued by police and port workers.

"He was freezing and close to drowning," Mr Ignacio told local media. "He was hauled into a boat and wrapped in a blanket. He was saved thanks to Nanook."