Hopes of finding survivors from a missing Argentine submarine with 44 crew members aboard have been revived after the navy said it had detected what could be distress calls.
The search has, however, been complicated by stormy conditions, Argentine navy spokesman Enrique Balbi said on Saturday.
However, the defense ministry said it had detected seven satellite-transmitted signals that may be an attempt by the submarine to resume contact.
The signals were received at 10:52 am (1352 GMT) and 3:42 pm (1842 GMT) on various naval bases with the help from US satellite communication experts, but they did not lock in, thus preventing a full connection.
"Right now, we are working to pinpoint the exact location of what is emitting the signals," presuming that it could be the missing sub, the ministry said.
Early Sunday, the US Southern Command said it was sending a second Navy P-8A Poseidon aircraft to join the search. The Florida-based plane and a crew of 21 are to reach Argentina later in the day.
A NASA P-3 research aircraft is already participating in the search, Southern Command said.
The California-based Undersea Rescue Command earlier said it was deploying two underwater crafts designed to rescue trapped submarine sailors at different depths, as well as a remotely-operated underwater robot known as an ROV.