A Russian navy officer says rescuers are hours away from reaching seven Russian sailors trapped aboard a small submarine on the Pacific Ocean floor with a dwindling air supply.

But Rear Admiral Vladimir Pepelyayev says there is enough air on the sub to last into Sunday.

U.S. and British undersea rescue vessels are on ships trying reach the submarine, which is stranded off the Kamchatka Peninsula in Russia's far east.

The submarine is stuck nearly 200 meters below the surface, its equipment tangled with an antenna from a military coastal monitoring system.

The incident comes nearly five years after a Russian nuclear submarine, the Kursk, sank in the Barents Sea following an explosion. All 118 men on board died.

Some information for this report provided by Reuters and AFP.