Argentina's navy has announced that searchers have found the missing submarine ARA San Juan deep in the Atlantic a year after it disappeared with 44 crewmen aboard.

The navy said on Saturday that the vessel was detected 800 metres down in waters off the Valdes Peninsula in Argentine Patagonia.

It said the submarine was found by a remote-operated submersible from the American ship Ocean Infinity, which was hired for the latest search for the missing vessel. The navy says it is a "positive identification".

The discovery was announced just two days after families of the missing sailors held a commemoration one year after the sub disappeared, on November 15, 2017.