Frantic hunt on

Indonesia's desperate search for a missing submarine and its 53 crew was focused on a signal from an unidentified object yesterday, with just hours to go before the stricken vessel's oxygen reserves ran out.

Nearly two dozen warships were taking part in the ramped-up hunt, as Australia and the United States joined the search off the coast of Bali where the sub disappeared more than two days ago during training exercises.

The military said it had picked up signs of an object with high magnetism at a depth of between 50 and 100 metres.

Ships equipped with specialised tracking equipment were deployed in the hope that it may be the KRI Nanggala 402, which was equipped with oxygen reserves that could last until early today, authorities said.

The search zone covers an area of about 10 square nautical miles (34 square kilometres).

"We've only got until 3:00 am tomorrow (Saturday) so we're maximising all of our efforts today," Indonesian military spokesman Achmad Riad said earlier.

An oil spill spotted where the submarine was thought to have submerged pointed to possible fuel-tank damage, fanning fears of a deadly disaster.

There were also concerns that the submarine could have sunk to depths believed to be as much as 700 metres (2,300 feet) -- well below what it was built to withstand.

The German-built vessel was scheduled to conduct live torpedo exercises when it asked for permission to dive. It lost contact shortly after.

Besides, US, Australia, India as well as neighbouring Singapore and Malaysia have already dispatched ships that are expected to arrive at the weekend, including the city-state's MV Swift Rescue -- a submarine rescue vessel.

Indonesia is also relying on a pair of its own submarines -- among the five in its fleet -- to aid in the hunt.