Boris Johnson has accused David Cameron of setting up a commission on the future of Britain’s airports “to provide cover for a U-turn on Heathrow”.

Mr Johnson, the Mayor of London, criticised ministers following suggestions that an independent commission will next week call for a major expansion of Heathrow Airport.

He said that any decision to base the UK’s aviation policy on expanding Heathrow Airport would be “environmentally disastrous and wrong for the country”.

Any signs that the Government could consider building new runways at Heathrow will be met with fury by Mr Johnson.

The Mayor has previously warned that he would be prepared to do everything in his power to stop the west London airport growing.

Downing Street will be concerned that it could lead to a series of confrontations with Mr Johnson ahead of the 2015 general election.

The Airports Commission, chaired by Sir Howard Davies, is due to publish its interim report on Tuesday. It is expected to shortlist only Heathrow expansion options.

Mr Johnson, who favours a new four-runway airport in the Thames Estuary – dubbed “Boris Island” – said that he is “philosophical” about the findings of the commission.

However, he said: “I’ve long thought that the purpose of the exercise [in setting up the commission] was to provide cover for a U-turn on Heathrow. Expansion of Heathrow would be wrong for London and wrong for the country.”

Speaking yestersay in Wandsworth, south London at a cycling event, Mr Johnson added: “I don’t want to pre-judge what Sir Howard might say but Heathrow expansion is not deliverable and is environmentally disastrous.”

Although supported by the last Labour government, expansion at Heathrow in the form of a third runway, was initially ruled out by the coalition Government in May 2010.

Mr Johnson is understood to have met Patrick McLoughlin in recent days to express his concerns about any expansion of Heathrow.

“I cannot conceivably believe that Howard Davies would inflict the misery of a third runway at Heathrow, let alone a fourth, on a million people or more in west London,” Mr Johnson said this week. “I’ve engaged in this process in good faith.”

A number of west London MPs including Justine Greening, the International Development Secretary, could face being voted out of Parliament if Heathrow expansion goes ahead.

There have even been suggestions that Mr Johnson could consider running as an MP in 2015 so that he can fight the runway plans from inside Westminster.

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Photo Credit: A jumbo jet takes off shortly before midday from Heathrow Airport in west London. Toby Melville / Reuters