Argentina's navy says that brief satellite calls did not come from a missing submarine with 44 crew members on board.
The communication attempts received were originally thought to indicate that the crew was trying to re-establish contact and had prompted celebrations by family members and officials.
But Navy spokesman Enrique Balbi said on Monday that the seven low-frequency satellite signals were analysed and do not correspond to the submarine, the ARA San Juan.
Authorities last had contact with the sub on Wednesday as it was sailing from the extreme southern port of Ushuaia to the city of Mar del Plata.
Admiral Gabriel Gonzalez of the Mar del Plata Naval Base said on Monday that the submarine had sent an alert on Wednesday about an unspecified breakdown.
On Sunday, search units were largely relying on information gathered from a British polar exploration vessel, the HMS Protector, which was equipped with an underwater search probe and following the path taken by the submarine, the ARA San Juan.
According to a statement from the Royal Navy, said HMS Protector Commander Angus Essenhigh:
"Our thoughts remain with the crew of the ARA San Juan and their families at this time."
The gesture has attracted attention since the nations fought a bloody war in 1982 after Argentina invaded the Falklands Islands.
As submarine rescue has developed significantly in the last years, NATO's Submarine Rescue System (NSRS), in which Britain, Norway and France are partners, can now get to a vehicle anywhere in the world in 72 hours.
Submariners can escape in special immersion suits up to 180 metres, but they won't survive deeper than that.
NEMO mates onto the hatch of the submarine drains the water and allows the submariners to escape into its pressurised rescue chamber. on the country's north-east coast.
Admiral Gonzalez also confirmed the US Navy's Undersea Rescue Command had been deployed to the search area, along with aircraft from Argentina, Brazil and the US, and 11 surface vessels.
Among the 44 crew members is Eliana Krawczyk, the first female submarine officer in Argentina.
Authorities said the submarine left the extreme southern port of Ushuaia on Wednesday and lost contact as it was heading to Mar del Plata, a city on the country's north-east coast.