BUENOS AIRES, Argentina • Military ships and aircraft have stepped up search efforts in difficult, stormy conditions, off the coast of Argentina for a navy submarine missing for three days.
The vessel, which was patrolling off Patagonia with 44 crew members, last made radio contact on Wednesday, Captain Enrique Balbi, a spokesman for the Argentine navy, said in a television interview.
Two planes were deployed on Thursday afternoon to begin searching for the submarine, ARA San Juan, one of three in Argentina's fleet.
Rescuers were hindered by poor visibility and they resumed the search on Friday morning, using vessels as well as aircraft.
The submarine's last known location was 240 nautical miles off the coast, according to the navy.
The ARA San Juan was travelling from the Patagonian city of Ushuaia to Mar del Plata, in Buenos Aires province, conducting a routine security patrol.
Submarines often ply the Argentine coast to detect illegal fishing.
Sailors who have served aboard submarines called the lengthy disappearance highly unusual.
"This has never happened to us before," said 30-year submarine veteran Pedro Alcaraz, who retired in 1997 as a chief petty officer. "We've lost communication for many different reasons, but never for this long."
The United States, Chile and Britain offered logistical support, according to Argentina's Foreign Ministry. But, so far, no foreign militaries have joined the search, according to a Defence Ministry official.
ARA San Juan's crew member Eliana Maria Krawczyk is Argentina's first woman submarine officer. Her father Eduardo Krawczyk told the Todo Noticias network last Friday that the family was hoping for the best.
"Let's pray together for everything to be resolved and for nothing to have happened to anyone in the crew," he said. "In the sea, they're all brothers. It's not like a boat that sails on the surface. Submarines have greater risks."
The rescue mission last Friday included the destroyer ARA Sarandi, which has a helicopter on board, and corvettes ARA Rosales and ARA Drummond. Argentine officials also asked civilian vessels in the area to monitor for possible radio signals from the submarine.
Navy officials attempted to downplay the severity of the situation after media outlets broke news of the search early last Friday.
"We are not talking about an emergency right now, but rather we are handling it as a loss of communication with the submarine," Rear Admiral Gabriel Martin Gonzalez, who oversees submarine crews, told reporters gathered outside the naval base in Mar del Plata.
But concern is growing over the crew's fate, especially since their vessel had backup systems if the main communications equipment failed, and should have been able to send a distress signal.
"As the hours tick on, one starts to be inclined to think we may be talking about a tragedy - but there is still hope," said Mr Fernando Morales, a navy expert and vice-president of the Argentine Navy League. "For now, what we're speculating is that it is floating", and has not sunk.