A rescue operation has been launched to evacuate workers from a floating oil production ship in the North Sea which is partly adrift in storms.

Three rescue helicopters from Shetland and RAF Lossiemouth have been scrambled to lift off non-essential crew from the Gryphon Alpha after it broke some of its moorings in the gales battering northern Scotland. Aberdeen coastguard said there was no immediate pollution risk.

Rolling seas were making the vessel pitch more wildly and heavily after it lost the moorings. The vessel, which has 114 crew, is a floating oil storage and offloading facility for North Sea rigs which are connected by underwater oil pipes.

The vessel, the oldest floating production ship in the North Sea, is about 110 miles east south east of Sumburgh on Shetland. A surveillance aircraft from RAF Waddington in Lincolnshire has been co-ordinating the evacuation.

A coastguard spokesman said: "The issue was to do with the winds last night: they became parted from some of their mooring bouys. They're currently under control from their thrusters.

"They're just a bit concerned that if the situation deteriorates, as they have lost some of their anchors, they would rather have the non-essential personnel off."

Gales across Scotland overnight peaked with hurricane force gusts of more than 100mph across Shetland and Orkney. The area around the Gryphon Alpha is still enduring gales, but the winds have lessened to about 41mph, gusting to 58mph.

"At the moment, there's no cause for concern in terms of pollution. At the moment, it's still focusing on search and rescue. We're bearing the pollution issues in mind," the coastguard spokesman added.

One of the helicopters has come from the coastguard station at Sumburgh, on the southern tip of Shetland, and a second is an oil industry Super Puma operated by Bond from the same airport.

The third helicopter has come from Lossiemouth. Both RAF Lossiemouth and Shetland coastguard station are under threat of closure or a significant reduction in role from the spending cuts. The Nimrod air surveillance planes traditionally used in these operations were scrapped last month.

There are new fears about the risk of an oil industry disaster in the North Sea and north-east Atlantic after the Times reported that an oil exploration company wanting to drill a deep well west of Shetland admitted that 180 million gallons of oil could spill if it was breached.

The US firm Hess has made the disclosure in its application for a drilling licence to the Department of Energy and Climate Change. It said that in a worst case scenario, the oil could reach as far south as Norfolk and destroy seabird colonies across northern Scotland.