Six seamen are missing after a cargo vessel sank off the north Wales coast in gale force weather but two crew have been rescued.

The crew of the 81-metre (265 ft) carrier, the Swanland, raised the alarm at about 02:00 GMT.

They reported the hull was thought to have cracked in bad weather and the ship was taking on water.

The carrier, with 3,000 tonnes of limestone onboard, disappeared 30 miles north-west off the Lleyn peninsula.

Two RNLI lifeboats, with four search and rescue helicopters and two commercial boats, are searching for the remaining six crew.

Holyhead coastguard, who are co-ordinating the rescue, said they were very concerned for the missing men.

Jim Green, from the station, said: “We are very concerned for the safety of the other six crew members.”

“We know that at least some of them are wearing immersion suits and have strobe lighting with them, however sea conditions are challenging at best,” he added.

The coastguard sent out a mayday relay and several vessels responded and went to the scene to assist.

When the vessels arrived, they found two liferafts and some floating debris.

Rough seas

One helicopter from RAF Valley on Anglesey and another from Dublin Coastguard arrived at the scene, as well as RNLI lifeboats from Pwllheli and Porthdinllaen.

Two people who were clinging to liferafts were rescued and airlifted to RAF Valley on Anglesey. The search is continuing for the remaining six crew members.

The coastguard report very difficult conditions in the dark with rough seas and high winds.

In August 2010, the Swanland’s engines failed and it came close to grounding on rocks off the Lizard peninsula in Cornwall.

According to one shipspotting website, the vessel was built in the Netherlands and is owned by a company, Torbulk, in Grimsby.

RAF Valley is where Prince William is based as a search-and-rescue pilot but it is not clear if he was on duty this weekend.