An abnormal sound detected underwater by an worldwide agency on the morning of November 15, around the time that the ARA San Juan sent its last signal and in the same area, was "consistent with an explosion", navy spokesman Enrique Balbi told reporters.
He said seven ships are mapping the bottom of the ocean where the submarine might be found and that weather conditions are expected to worsen Sunday.
The ARA San Juan search location straddles the edge of the continental shelf, where ocean depths vary, but reach as deep as 3,000 metres.
Chances of finding the crew with a viable air supply may be dwindling.
The ARA San Juan submarine stopped communication mid-last week, but the search for the missing sub grew more frantic over the weekend after it had failed to make contact or surface, as would be expected if it was distressed.
If the vessel remained intact, its crew would have only enough oxygen to survive submerged for a little more than a week.
Friday, Balbi said he wouldn't entertain speculation about where the San Juan is, despite knowing roughly where the noise came from.
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Saturday marked the 10th day since the ARA San Juan submarine reported its last position off Argentina's southern coast.
Argentine Naval spokesperson Captain Gabriel Galeazzi said on Tuesday that it was "an arduous task, it is not simple and takes time".
Navy spokesman Enrique Balbi said there was no evidence the possible explosion was linked to an attack and they would continue the search until they knew for sure what had happened. But the Argentine defence minister later said the calls did not come from the submarine.
On November 15, it said, "two CTBTO hydroacoustic stations detected an unusual signal in the vicinity of the last known position of missing Argentine submarine ARA San Juan".
Balbi said that the news of the abnormal sound was consistent with a separate report received Wednesday of an "acoustic anomaly" in the same area and around the same time.
The Vienna-based Comprehensive nuclear Test-Ban Treaty Organisation (CTBTO) runs monitoring stations equipped with devices including hydrophones - underwater microphones that scan the oceans for sound waves.
The Argentine ministry said that Russian Federation had proposed dispatching a high-technology survey vessel to assist in search operations, and Argentine President Mauricio Macri welcomed the assistance.
It disappeared in the San Jorge Gulf area, 240 nautical miles (432 km) southeast of the Valdes peninsula, in the South Atlantic.