Argentina missing sub sent seven failed satellite calls

The ARA San Juan, a German-built diesel-electric vessel, not heard from since Wednesday (Argentina Navy via AP )

Argentina's Navy has detected seven brief satellite calls that officials believe may have come from a missing submarine with 44 crew members on board.

The communication attempts "indicate that the crew is trying to re-establish contact, so we are working to locate the source of the emissions," the Navy said on its Twitter account, adding that the calls lasted between four and 36 seconds.