The Argentine navy says an event consistent with an explosion was recorded near where Argentine submarine disappeared last week with 44 crew on board, BBC reports.
A navy spokesman said an "abnormal, singular, short, violent, non-nuclear event" had been detected in the south Atlantic.
The ARA San Juan disappeared last Wednesday.
More than a dozen countries including Russia and the US have sent assistance.
On Thursday, a US navy aeroplane detected an "object" near the submarine's last-known location, the news agency Reuters reported. It said a witness on board the plane had said the object could not be identified.