More than 11,000 British jobs were under threat last night after the Pentagon tore up the world’s biggest defence contract to allow an American company to rebid.

Airbus stands to lose an £18 billion contract to build tankers for the US Air Force, awarded only four months ago, after aggressive lobbying by US politicians, including the presidential candidates John McCain and Barack Obama.

Up to 14,000 other jobs are threatened by the move, mainly in the US, France and Germany.

Work on the vast project would have safeguarded thousands of jobs at factories in North Wales and Bristol. Airbus’s British operations were to make wings for the fleet of tankers, with the initial value of the contract to the British economy estimated at more than £4 billion.

The contract was cancelled by the Pentagon, which cited irregularities with the bidding process. Boeing will be allowed to rebid and is expected to secure the contract.

Unions reacted with fury. John Wall, general secretary of the Confederation of Ship Building and Engineering Unions, which represents the Airbus workers, said: “Airbus beat Boeing in every single major feature in this competition and I don’t see that changing, but what has changed is the political pressure to buy American.

“This win was very, very important for the UK as it ensured we would stay right at the top of the world aerospace league and was critical to securing jobs and our industrial capability. As the US economy gets worse the politicians have wrapped themselves in the flag and backed Boeing, which is very frustrating.”

The news comes at a critical time for the British economy, with thousands of jobs expected to be lost in manufacturing because of a sharp downturn in demand. Employers are urging the Bank of England to alleviate their plight by cutting interest rates at its monthly policy meeting today. The Government is understood to have helped Airbus to lobby for the contract by emphasising the close defence links between the two countries.The decision to award such a large contract to Airbus and its partner Northrop Grumman amazed the defence industry as the Pentagon usually buys only American-made weaponry.

Boeing, the giant American aircraft manufacturer, complained that the bidding process had been unfair and, after a review, Robert Gates, the US Defence Secretary, announced that the competition would start again. This is was seen by many defence analysts as a concession to Boeing’s political backers, who want the Pentagon to go back to its “buy American” policy.

Senators including Mr Obama and Hillary Clinton, as well as numerous congressmen, have questioned the Pentagon’s decision to jeopardise American jobs by giving the contract to a foreign company.

Air-refuelling tankers may be one of the less exciting aircraft in the US fleet, but the contract has become, arguably, the most scandalous and difficult in history.

When the airline industry collapsed after the terrorist attacks of 9/11, Boeing agreed to sell unwanted 767 jets to the Pentagon as refuelling tankers.

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