US Navy P-8 Poseidon patrol planes have joined an global search for the Argentine Armada submarine San Juan, and the Navy has prepared submarine rescue vehicles and four uncrewed underwater vehicles (UUVs) to assist in the search as well.
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.
The navy said an electrical outage on the diesel-electric-propelled vessel may have downed its communications, though protocol calls for submarines to surface if communication is lost.
On Saturday, several satellite signals thought to have come from the sub were detected near the Valdez peninsula. "We are analyzing more closely to reliably determine that they weren't calls coming from the submarine", said Adm. Gabriel Gonzalez, chief of Mar del Plata Naval Base, in a statement to press this morning.
Research is continuing in an area of 300 km in diameter off the coast of argentina.
The U.S. government is supporting a request from the government of Argentina for global assistance to the ongoing search for the missing submarine and possible rescue opportunities once the vessel and crew are located.
Earlier Saturday, Navy spokesman Enrique Balbi said the area being searched off the country's southern Atlantic coast has been doubled as concerns about the fate of the submarine and its crew grew.
A distress signal detected Monday by Argentina's navy may have come from a missing military submarine. "That is why we are now giving priority to the search for the sunken submarine".
Galeazzi said the search would continue until the Argentine sub is found.
The Argentina-born Pope Francis mentioned the missing vessel in his weekly Sunday prayers at the Vatican in Rome.
The Navy patrol planes join the NASA P-3 Orion "flying lab" that had been in Argentina for Operation IceBridge.
The British polar ice patrol ship HMS Protector, equipped with sonar equipment, is also providing assistance.
Balbi said the position was in line with the course the submarine would have taken to reach its base in the northeastern city of Mar del Plata after reporting a breakdown last week and then going incommunicado.
RESCUERS searching for a missing submarine have picked up noises which could have been made by crew knocking on the hull - sparking hope the 44 on board are still alive.
The US official said that the waters of the Atlantic Ocean where the sounds originated are extremely deep.
The submarine's fate has gripped the nation, and President Mauricio Macri visited the relatives and prayed with them on Monday.