Naval authorities were racing to figure out how to raise the vessel, the AS-28, from a depth of some 188 meters off the Kamchatka peninsula. The US Navy was scrambling to send an unmanned underwater vehicle to help rescue efforts, and Britain and Japan also rushed to help.

``There is air remaining on the underwater apparatus for a day - one day,'' said Captain Igor Dygalo. ``The operation continues.''

Dygalo and other officials had said earlier in the day that the mini-submarine had enough air to last for five days.

The confusion apparently stemmed from the fact that there were seven people aboard the vessel, which normally carries a crew of three.

The submarine was disabled after it was launched from a ship Thursday in a combat training exercise. Its propeller became entangled in the fishing net.

It was too deep to allow the sailors to reach the surface on their own or for divers to reach it, experts said. Still, there was contact with the sailors, who were not injured.

Two surface ships were sweeping the area with nets in the hope of wresting the trapped vessel from the sea floor, Dygalo said, and the rescue effort would continue into the night.

Earlier, Russia appealed to the United States and Japan for assistance.

Dygalo said the US Navy agreed to fly a robotic rescue vehicle from San Diego to the accident area off the Kamchatka peninsula, but he did not say when it was expected to arrive.

And a British aircraft with unspecified rescue equipment was not expected before Saturday.

At Moscow's request, Tokyo dispatched a vessel carrying submarine rescue gear and three other ships to join rescue efforts, but they were days from the scene, said a spokesman for Japan's Marine Self Defense Force.

The mini-submarine is in Beryozovaya Bay, about 75 kilometers south of Kamchatka's capital, Petropavlovsk-Kamchatsky.

The accident occurred almost exactly five years after the nuclear submarine Kursk sank to the bottom of the Barents Sea after explosions on board, killing all 118 seamen aboard in a painful blow to the Russian navy.

Some sailors survived for hours after the accident as air ran out, and Russian authorities came under sharp criticism for their handling of the crisis.