Hopes that the missing Argentinian submarine may be found have been dashed after investigators conceded they "have no trace" of the vessel.

The ARA San Juan went missing seven days ago with 44 crew on board, and the fear is that the oxygen on board has now run out.

Clues emerged overnight that pointed to the possible whereabouts of the missing sub — a sound signal, flares and a "heat spot" — but these have been dismissed by officials.
"At the moment we have no trace of the submarine," navy spokesman Enrique Balbi told reporters Wednesday morning, according Argentinian newspaper Clarin.

"We are still in this search and rescue phase. We are in the critical part. The seventh day is being fulfilled today regarding oxygen, assuming that seven days ago it has no capacity to go to the surface and renew oxygen. But we do not rule out the other options, which may be on the surface."

Navy spokesman Enrique Balbi talks to journalists in Buenos Aires about the hunt for the sub. Photo / AP
Navy spokesman Enrique Balbi talks to journalists in Buenos Aires about the hunt for the sub. Photo / AP

Balbi confirmed that search vessels had detected a sound signal and three flares, but they were determined to have not come from the missing submarine.
He also discredited reports of a "heat spot" coming from the ocean floor.

About 30 boats and planes and 4000 people from Argentina, the US, the UK, Chile and Brazil are part of the search.

The monster multinational effort has included sonar, thermal imaging and magnetic technologies, but none has provided any trace of the vessel.

"Of those three media, in acoustic form with the sonars, infra-red with the thermal image and the detector of magnetic anomalies, there was no type of contact that is supposed to be the submarine," Balbi said, in comments translated into English.
Despite the frustrating lack of leads as investigators scour the ocean, Balbi has not given up hope.

"We're considering three scenarios: the submarine is above the surface with its engines running, adrift at sea without propulsion or submerged on the bottom of the ocean," he said.

He noted that weather was favourable for the search yesterday, but that conditions would become "complicated" today.
Argentina's Navy lost contact with its ARA San Juan submarine at 7.30am last Wednesday after it left the port of Ushuaia in the country's hostile south to sail around the tip of the Patagonia region.

The 34-year-old German-built diesel electric submarine last made contact with authorities when it was about 480km from the Argentinian coast to flag a mechanical breakdown with its batteries.