Update 10.30pm: Five fishermen have been rescued after their boat lost power and was drifting in seas off the Donegal coast this afternoon.
Three lifeboats including the Lough Swilly lifeboat, the Arranmore lifeboat and the Portrush lifeboat rushed to the troubled vessel.
The boat was a 45ft crabber based in Mayo but which was fishing 20 nautical miles off Fanad Head around 2pm when it got into trouble.
Heavy seas, as well as gale-force winds, hampered the rescue mission.
The Lough Swilly lifeboat eventually managed to get a tow-line secured and the vessel is now being brought back to port.
It is due to berth in the early hours of Sunday dependent on weather conditions.
Rescue mission underway for five fishermen off coast of Donegal
Update 4.50pm: A rescue mission has been launched off the coast of Co Donegal after a fishing vessel broke down 20 miles out to sea in rough seas.
The vessel, understood to be an Irish registered crabber, lost power 20 nautical miles north-west off Fanad Head.
The boat has five crew members on board.
The boat sent out a mayday signal just after 2pm.
Members of the Lough Swilly RNLI crew and also the Portrush lifeboat have responded to the call.
Locals say that weather conditions at sea are very challenging with winds of up to 60mph reported as well as heavy sleet.
It is hoped a line can be deployed to the boat to tow it back to safety.
However, there are serious concerns because of the weather conditions.