Russian nuclear sub crippled

Some 11 Oscar-II class submarines are thought to be in service

A Russian nuclear submarine has broken down during exercises in the Barents Sea, and is trapped on the sea floor with a crew of more than 100 on board.

The Oscar-II class submarine was not carrying any nuclear weapons and there was no immediate danger, said the head of the Russian navy's press service, Igor Dygalo.

He said no radiation leaks had been reported.

Rescue ships are rushing to the area to assist the crippled submarine, named Kursk, which is in radio contact with surface vessels.

Oscar-II class submarines usually carry a crew of 107 personnel, including 52 officers.

A correspondent for Russian NTV television reported the crew had been forced to ground the Kursk after problems with its torpedo tubes flooded the vessel's front section.

Analysts say a submarine would normally surface in an emergency and the fact that the Kursk has run aground is an indication that the situation is serious.

Reactor shut down

The navy did not say when the incident happened or where in the Barents Sea the submarine was located.

Oscar-II class

Length 155 metres

Displaces 24,000 tons

Armed with guided missiles and torpedoes

Designed to strike against surface forces especially carriers

Mr Dygalo said the vessel's nuclear reactor had been shut down and was under control, adding that the reactor was not the source of the problem.

The Russian navy has been conducting major exercises in which the submarine was participating, Mr Dygalo said.

The Kursk was built in 1994 and went into service in 1995, making it one of the newest vessels in the Russian navy.

It is capable of carrying up to 24 underwater to surface guided missiles, which can be armed with nuclear or conventional warheads, and can stay under water for six months at a time.

String of incidents

The BBC Moscow correspondent, Robert Parsons, says the accident is the latest in a string of incidents that have plagued Russia's submarine fleet.

He says a shortage of funds has meant that vessels frequently don't get the sort of service needed to keep them seaworthy.

In one major accident in April 1989 a Soviet nuclear submarine, the Komsomolets, sank to the bottom of the Barents Sea after catching fire 210 miles north of Norway.

Forty-two of the 69 Soviet sailors aboard died in the accident.