An Argentine submarine with 44 crew on board was missing in the South Atlantic two days after its last communication, prompting the navy to step up its search efforts late on Friday in difficult, stormy conditions. The ARA San Juan was in the southern Argentine sea 432 km from the Patagonian coast when it sent its last signal on Wednesday, naval spokesman Enrique Balbi said.

A Nasa research plane has joined the search for the vessel. Pic/AFP