Noises detected by Argentine Navy probes did not come a missing submarine, authorities in Buenos Aires said on Monday.
The vessel went missing last week with 44 sailors on board.
The "noises" were analysed and experts determined they did not come from tools being banged against the hull of a submarine as was previously reported by some media, Navy spokesman Enrique Balbi said.
He added that the sound likely came from a "biological" source.
The noise was heard in the South Atlantic about 220 miles from the Argentine coast and at a depth of about 650ft. A US Navy P-8 Poseidon aircraft was sent to help in the effort to isolate the source of the sounds.
"We all had hope, but unfortunately this comes from believing sources that are not trustworthy," Balbi said. "Some sources were saying that this was banging on the hull in Morse code signals."
The ARA San Juan, which went missing on Wednesday as it sailed from Ushuaia to Mar del Plata, reported a battery failure before it disappeared, a naval official confirmed on Monday.
The diesel-electric submarine has enough food, oxygen and water to last 90 days on the ocean surface. However, when submerged, its oxygen supply will only last for seven days.
Pope Francis, a native of Argentina, has offered his "fervent prayers" for the missing crew.