The crew of missing submarine ARA San Juan reported a fire in their final message, according to Argentinian media.
The final contact from the vessel, which has 44 crew members on board, reportedly said seawater had entered the ventilation system, causing a battery on the diesel-electric submarine to short-circuit and spark a fire.
According to news channel A24, it was received on 15 November.
It comes after the Argentinian navy said the captain reported an electrical problem in a battery compartment before it went missing. The submarine was ordered to return to its base in Mar del Plata.
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Navy spokesman Enrique Balbi told reporters that the captain said water had entered through the vessel's snorkel when its batteries were being changed.
He said the captain later communicated by satellite phone that the issue had been resolved.
Fifteen countries are now involved in the search for the missing vessel but there have been no signs of it or any debris.
The search area, which is concentrated 250 miles from Argentina, has been extended 22 miles from where an explosion was detected.
Hopes for survivors are distant , with sailors only having enough oxygen to last up to 10 days if the submarine was intact underwater.
In his first public comments on the missing sub, President Mauricio Macri said: "The disappearance and current search for the ARA San Juan submarine has touched all Argentines.
"It's a difficult moment for all but, obviously, especially for the families of the 44 crew members.
"I'm here to guarantee you that we will carry on with the search, especially now that we have the support of all the international community."
The German-built San Juan, a TR-1700 class submarine, was commissioned in 1985 and refitted in 2014.