BBC News
Hope they work everything out. First thing I thought was another Kursk.Submarine issues call for help
A major rescue effort has been launched off Ireland after a Canadian submarine asked for assistance.
The Canadian Defence Force said HMCS Chicoutimi had suffered a mechanical failure and its crew were all safe.
A Royal Air Force Nimrod has been diverted to the area and a search and rescue helicopter from the Royal Navy base in Ayrshire is on its way.
The submarine, which was bought from Britain, is not nuclear-powered or carrying nuclear warheads.
The request for assistance came from the vessel some 100 miles north west of Ireland.
Neil Smith, a spokesman for the Faslane submarine base on the Clyde, said that Royal Fleet Auxiliary vessel Wave Knight had been turned round and was on its way to the scene.
A Type 23 frigate, HMS Montrose, is being sent from Faslane, accompanied by tug boat support.
"At this moment in time we don't have the exact details," said Mr Smith.
"We are in communication with the people on board.
"We are doing everything we can to assist them, and at this moment in time my colleagues are working hard to make sure that happens as quickly as possible."