BUENOS AIRES (REUTERS) - The hunt for an Argentine submarine missing since Nov 15 pressed on through gusting South Atlantic winds on Sunday (Nov 26) while families of the 44 crew members tried to cling to hope despite tough search conditions and worries about the sub's air supply.

The ARA San Juan had only seven days worth of oxygen when it reported its last position nearly 300 miles (483 km) off the coast. Relatives of crew members tried to focus on the possibility that the vessel may have been able to rise to periscope depth at some point after its disappearance, allowing it to refill its air tanks.

Argentina's weather service ordered an alert for "intense winds of between 50 and 90 kilometers per hour, with gusts," in Chubut province, where search vessels were sailing from.

Reports of a sudden, violent sound detected underwater near the last known position of the vessel suggest it might have imploded after reporting an electrical problem.

But Oscar Vallejos, himself a naval veteran and father of San Juan crew member Celso Vallejos, told local TV that he and his family refused to believe his son would not return alive.

"Hope always high," said the burly Vallejos, his posture ramrod straight and eyes hidden behind sunglasses. A black baseball-style cap identified him as a navy war veteran.

Other crew family members were less sure.

"We are in a state of total uncertainty," Maria Victoria Morales, mother of Luis Garcia, an electrical technician aboard the missing cold-war-era submarine, told Reuters by telephone.

The US Navy has deployed unmanned underwater vehicles, or mini subs, equipped with sonar to join the search. A Russian plane arrived in Argentina on Friday carrying search equipment capable of reaching 6,000 metres below the sea surface, according to the Argentine navy.

The international search effort includes about 30 ships and planes manned by 4,000 personnel from 13 countries including Brazil, Chile and Great Britain.