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."