The Pentagon has cancelled a defence contract that would have secured 11,000 British jobs following fierce political lobbying by American companies.

Airbus, the European aircraft manufacturer, won a contract to supply the United States Air Force with refuelling tankers earlier this year. The wings for all 179 planes would have been built in the UK in a deal worth over £4 billion to the British economy.

However, Robert Gates, the US Defence Secretary, said that he was cancelling the contract because it had become too “emotional”.

Defence analysts said that the Pentagon seemed to be succumbing to political pressure to protect American jobs. Boeing, the giant US-based aerospace company, lost the contract to Airbus and is believed to have spent millions of dollars lobbying politicians in Washington DC to get it recompeted.

Bernie Hamilton, national officer for the Amicus union, which represents Airbus’s British workers, said: “Politics has over taken the right thing to do and the British government needs to reflect on that.”

The $35 billion tanker contract is the largest defence project in the world and it is also the USAF’s highest priority. Its existing fleet of Stratotanker refuelling planes have an average age of 47 years and urgently need to be replaced.

Northrop Grumman, a US-based defence company, and EADS, which owns Airbus, won the contract with their A330 aircraft and the wings were to be made at the Broughton factory in North Wales.

This work would have given Broughton many years of additional work and helped to secure 11,000 jobs at one of the UK’s largest manufacturing sites.

The deal was so important to UK industry that both Tony Blair and Gordon Brown have promoted the Airbus aircraft in discussions with the White House.

When Airbus won the tanker contract earlier this year, Boeing protested and the Pentagon was forced to put it out for tender again. This was originally planned as a six-month process with a decision made before a new president took office.

However, the Pentagon has now cancelled the entire contract and will delay everything until after the presidential election.

A new competition will then take place next year, which will give Boeing time to offer a newer, larger aircraft.

“Just how many chances does Boeing get to win this contract,” one defence industry insider said. “They lost it fair and square but now they get to offer a new plane to see if they can win with that. This competition has become very dirty.”

British defence officials have warned that if the Pentagon keeps blocking European companies from large projects there could be retaliation.

Amicus said that it too would take up the issue with Peter Mandleson, the European trade commission.

Mr Hamilton said: “Is it fair for American companies to compete openly for defence contracts in this country when they are so protectionist in their own?”

Senator Barak Obama, the Democratic presidential candidate, has questioned the decision to give the initial contract to Airbus and analysts believe that a President Obama would ensure Boeing won the tanker deal.

Senator John McCain has said that he believes the Pentagon should make the best decision for taxpayers. He cancelled an earlier tanker deal for Boeing and it subsequently emerged that the company had secretly offered a job to the Pentagon official tasked with arranging the terms. The official and a Boeing executive were jailed over the affair.

Robert Gates said: “It is my judgment that in the time remaining to us, we can no longer complete a competition that would be viewed as fair and objective in this highly charged environment. The resulting ‘cooling off’ period will allow the next administration to review objectively the military requirements and craft a new acquisition strategy.”

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