Britain is preparing to lodge legal claims over tens of thousands of square miles of the Atlantic sea-bed, threatening to reignite the Falklands dispute with Argentina.

The claims, to be negotiated at the United Nations, would enable Britain to exploit oil and mineral reserves up to 350 miles from the coast of its territories.

The gathering struggle over the Atlantic follows the emergence earlier this year of a high-profile scramble for the sea-bed under the Arctic.

Last month, a Russian submarine raised a titanium flag on the sea-bed under the North Pole. Moscow has also taken out advertisements in western newspapers extolling its historic claims to the region.

Its case is opposed by four other Arctic countries – Canada, America, Norway and Denmark through its sovereignty over Greenland.

This week, preliminary talks open in Reykjavik between Britain, Iceland, Ireland and Denmark over the disputed Hatton-Rockall plateau under the north Atlantic.

The area is close to Rockall, a British-owned speck of land 230 miles west of the nearest inhabited Scottish island.

British sovereignty over Rockall and larger areas such as the Falklands and Ascension Island gives the potential for rights over the sea-bed to be extended far beyond Britain’s own shores.

The new UN Commission on the Limits of the Continental Shelf, for which claims must be submitted, extends the current limit of 200 miles out to sea within which countries can claim oil and mineral rights.

Discussions over the waters around the Falklands will be held next year at the earliest.

Other countries participating in the Atlantic scramble for the sea-bed include France, Brazil and South Africa.

But the sea around the Falklands, which Argentina claims, is likely to be the most heavily contested. The territory is only 300 miles from the Argentinian coast, possibly bringing wide swaths of the South Atlantic into dispute.

Rights over the sea-bed and fishing rights were one of the factors that led to the conflict between Britain and Argentina in 1982.

The area around the Falklands is known to have huge quantities of oil, while the mid-Atlantic ridge, where Ascension is located, is rich in minerals. Under the UN treaty, as much as 2.7m squares miles could be at stake.

In recent years other countries which submitted claims to the ocean floors around remote imperial outposts have run into disputes with neighbouring nations. This happened last year to France over New Caledonia in the Pacific. Nearby Vanuatu, which in 1980 gained independence from France and Britain, complained.

The negotiations over the sea-bed are likely to be lengthy as the 200-mile limit can only be extended after complex arguments to determine the limit of the continental shelf by measuring the thickness of sedimentary rock on the sea-floor.

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