Watch Kiwi diver stab two sharks who go after his catch

A Kiwi diver has captured terrifying footage of the moment he was forced to stab two aggressive sharks in the head with a knife after they swarmed him.

The man was diving off the coast of Ascension Island near Brazil when he speared a tuna, the 'Daily Mail' reports.

While he was reeling in his catch a pair of Galapagos sharks started circling, trying to steal it before turning on him.

The predators appeared to spook the tuna, which was still alive, and the man became tangled in the speargun line as the fish tried to swim away frantically.

As he tried to surface the sharks started swimming directly at him.

He was forced to stab the sharks in self defence as they got close, and was then able to reel in the tangled tuna and scramble back on board the fishing boat with the help of friends.

This article was first published on nzherald.co.nz and is republished here with permission.