Argentina's navy says it's analysing the sounds detected on their sonar about 225 miles off the coast after the ARA San Juan vanished in the South Atlantic last Wednesday.
Navy spokesman Enrique Balbi said the noises were detected "on the edge of the (Argentine) shelf where there is an average depth of 200 metres".
Argentina's defense ministry said it detected seven failed "satellite calls" November 18, which officials believe came from a missing navy submarine.
"Unfortunately these conditions are expected to remain for the next 48 hours", Gonzalez said from the Mar del Plata naval base, where the submarine had been heading toward before vanishing.
Speaking of a "communication failure", the navy said the submarine is not considered lost, while Balbi denied a report that there may have been a fire onboard.
Submarine ARA SAN JUAN, TR-1700-class diesel-electric submarine in active service with the Argentine Navy, built 1983, displacement: 2140 tonnes (surfaced) 2336 tonnes (submerged), armament torpedoes.
Doubts also surfaced over the origin of satellite signals that were initially thought to have come from the vessel.
"A warship has a lot of backup systems, to allow it to move from one to another when there is a breakdown", he said. On Board the submarine at the moment of departure was 44 members of the crew, why the ship did not respond and that could happen - is not known.
"There were seven attempts with a very weak signal that failed to connect", the officer said.
Crew members' relatives gathered at the Mar del Plata naval base, waiting for news.
Galeazzi said the search would continue until the Argentine sub is found. Built in Germany, it underwent maintenance in 2008 in Argentina.
"Yesterday's news was something of a respite for us, to know that there is life", Claudio Rodriguez, the brother of a crew member, said on television channel A24 on Sunday morning.
The ARA San Juan was returning from a routine mission to Ushuaia, near the southern-most tip of South America, towards Mar del Plata.
Argentina's defence ministry said it was working on tracing the location of the calls with an unnamed USA company that specialised in satellite communications.
Other vehicles assisting the search include a Brazilian P-3 and EADS CASA C-295 multi-purpose aircraft, a Chilean CASA C-295, multiple Argentine naval and air force aircraft (including two Grumman S-2E Tracker submarine warfare aircraft and C-130s), and the British Navy's ice patrol ship HMS Protector. Officials have said the crew should have an ample supply of food and oxygen.