THREE men have died after an accident involving an anchor chain aboard a gas rig standby vessel in the North Sea.

It happened on the Viking Islay in the BP Amethyst gas field - off the East Yorkshire coast, the boat's operators, Aberdeen-based Vroon Offshore Services, said.

The men were named as Finlay MacFadyen, 46, from Aberdeen, Robert O'Brien, 59, from Leven in Fife, and Robert Ebertowski, 40, from Gydnia, Poland.

The company said they were securing an anchor chain in the boat's bow when the accident happened. Humber Coastguard were alerted at 10.20am on Sunday.

Mr MacFadyen and Mr O'Brien, both coxswains, and boatman Mr Ebertowski were on board the vessel 25 miles off the coast.

Graham Philip, chief executive of Vroon Offshore Services, said: "This is a tragic incident, the details of which are still unclear.

"However, we are doing all we can to find out what happened and will co-operate with all relevant authorities to carry out a full investigation."

"Our thoughts currently lie with the family and friends of the men who have tragically lost their lives."

The men were taken to Hull Royal Infirmary by a Sea King helicopter based at RAF Leconfield, East Yorkshire, but died of their injuries.

The remaining nine crew were unhurt.

The Viking Islay, a 53-metre emergency response and rescue vessel, was supporting the Ensco 92 drilling rig on BP's Amethyst field when the accident happened.

It has now returned to the Humber port of Immingham where a full investigation will be carried out by the Marine Accident Investigation Branch.