Media playback is unsupported on your device Media caption Boris Johnson says the government should rule out uncertainty over the third runway

The government is to look at ways to expand the UK's airport capacity, amid suggestions the prime minister will perform a U-turn on his pledge not to build a third runway at Heathrow.

A commission chaired by ex-Financial Services Authority boss Sir Howard Davies will also consider a new airport to the east of London.

London Mayor Boris Johnson, who opposes expanding Heathrow, called the government's move a "fudge".

The commission will report after 2015.

Both the Conservatives and Lib Dems ruled out a third runway at Heathrow in their 2010 general election manifestos and the coalition agreement continued this commitment.

Reshuffle

However, business leaders and some Tory MPs have argued that increased airport capacity is vital to dragging the UK out of recession.

HOWARD DAVIES BIOGRAPHY Director of the London School of Economics between 2003 and 2011

Resigned after it emerged the LSE had accepted donations from a charity set up by the son of former Libyan leader Muammar Gaddafi

Chairman of the Financial Services Authority between 1997 and 2003

Deputy governor of the Bank of England between 1995 and 1997

Director general of the CBI between 1992 and 1995

Special adviser to Chancellor Nigel Lawson between 1985 and 1986

Also worked for the Treasury, Foreign Office and consultants McKinsey & Co

Several leading Conservatives, including Chancellor George Osborne, have hinted at a rethink over a third runway at Heathrow.

The controversy has intensified in recent days after Justine Greening, a fierce opponent of a new runway, was replaced as transport secretary by Patrick McLoughlin on Tuesday.

Critics, including Mr Johnson, have suggested this will prepare the ground for a change of Conservative Party policy.

Sir Howard, a former deputy governor of the Bank of England and director of the London School of Economics, will chair a body which will consider evidence from all sides and make recommendations to the government.

His commission will publish an interim report next year but no decision is expected until after the next election, due in 2015.

'Hub status'

David Cameron faced a number of queries on aviation policy during Prime Minister's Questions - the first since the end of the summer recess.

He told MPs that large infrastructure projects were "extremely difficult for individual governments to take and to deliver".

Mr Cameron added: "What we need to do is build a process that hopefully has cross-party support so we can look carefully at this issue and deliver changes that will address the problems of capacity we will have in future years and address the issue of the hub status in the UK."

Image copyright Other Image caption Sir Howard Davies is a former civil servant, banking regulator and voice of business

Asked by west London Labour MP John McDonnell whether he would rule out sanctioning a new runway while he was prime minister, Mr Cameron said he would "not be breaking my manifesto pledge".

The coalition's record on infrastructure came under attack from Labour leader Ed Miliband, who said the economy had been flagging for two-and-a-half years and coalition policy had "spectacularly failed".

The prime minister defended policies on job creation, apprenticeships and planning - and said all ministers must contribute to economic recovery plans no matter what department they are in.

Mr Johnson, who favours building a new airport east of London, has called for the issue to be settled once and for all by ruling out a new runway beyond 2015 - the scheduled date of the next election.

"What we need to do now is to end the uncertainty over Heathrow and say 'No, folks, it is all right. The policy is as it has been, which is to say no to a new runway both now and in the future.'"

'Limbo'

The BBC's chief political correspondent Norman Smith said Mr Johnson wanted to kill the idea of a third runway for ever and this was a "marked escalation" of the dispute within the party.

Questioned about a possible expansion during a visit to a school in east London, Deputy Prime Minister and Lib Dem leader Nick Clegg said: "My party's manifesto is against a third runway and the coalition agreement could not have been clearer: we have ruled out giving the go-ahead to a runway during this parliament. It will not happen during this parliament."

Labour's 2010 manifesto supported a third runway at Heathrow, but leader Ed Miliband later distanced himself from the policy, saying he had had "some very heated arguments" with predecessor Gordon Brown over the decision and had even considered resigning from the government.

Friends of the Earth's head of campaigns Andrew Pendleton said: "We don't need more airport capacity in the South East and London already serves more of the world's leading business centres than our European competitors.

"One of the biggest threats to the economy is climate change - airport expansion would undermine action to tackle it.

"The demands of the aviation industry are insatiable - if it's allowed to get its way, communities and the environment will be forced to pay the price."