LONDON - A large cargo vessel carrying 5,300 tonnes of timber has sunk in heavy seas in the English Channel, raising the spectre of a significant oil spill.

The "Ice Prince", went down in early hours of Tuesday after being abandoned by its 20-strong crew two days earlier, the coastguard said.

The stern of the 100-metre long, 6,400 tonne vessel, is on the sea bottom while the bow is above water, 26 miles off Portland Bill, Dorset.

Checks were being made later to see if any oil has leaked from its tanks after early attempts were abandoned because of the weather.

The Greek-registered ship, which had been travelling from Germany to Alexandria in Egypt, had 313 tonnes of fuel oil onboard.

"The agency's counter-pollution team will be urgently reviewing contingency plans at first light, and bringing forward any counter-pollution stockpiles that may be needed to help disperse any oil that surfaces, if any is released from her bunkers," the Maritime and Coastguard Agency (MCA) said.

The rough seas, gusting to Force 8, will help in any fuel dispersion, though the MCA said it could take a number of days before any debris reached the shore.

In addition, some of the 2,000 tonnes of sawn timber being carried on deck fell overboard before the vessel sank, causing potential problems in nearby shipping lanes.

"Portland coastguard along with their French coastguard colleagues ... are warning other approaching shipping of the hazards in the area ..," the MCA said.

The Ice Prince had been listing at 40 degrees and drifting at 3 knots after some of its cargo shifted and fell overboard in five-metre swells during the weekend.

Twelve of its crew were airlifted to shore on Sunday, including a Greek national with a broken leg.

A second vessel which had run into trouble, going aground off Great Yarmouth in Norfolk, was refloated at high tide on Monday evening with the help of two tugs, the MCA said.

The 9,600-tonne Isle of Man-registered car carrier "The City of Sunderland" has about 650 Nissan vehicles on board.