Cameron continues to battle against plans to expand Heathrow airport

Prime Minister David Cameron faces mounting pressure over having a third runway at ...

Prime Minister David Cameron faces mounting pressure over having a third runway at London’s Heathrow airport to deal with congestion problems.

Deputy PM Nick Clegg has ruled out any plans for the government to back an expansion of Heathrow.

A spokeswoman for Downing Street has confirmed there will be no short-term plans: "The Coalition parties have made a pledge not to have a third runway and that is a pledge we will keep. We don't see the argument for a third runway."

It is understood that hopes for a major expansion of one of the world’s busiest airports could see a Cabinet reshuffle next week.

This could concern Transport Secretary Justine Greening, who opposes the idea of building a third runway following her campaign in 2010.

The news comes as Senior Conservatives urge the PM to agree to a new "go-for-growth" strategy, as reported by the Independent.

A report which was released on Wednesday aired fears that the UK was "being left behind". The report showed an all-party committee of MPs and peers warning that "capacity constraints at Heathrow are restricting the UK's economic potential".

London Mayor, Boris Johnson, who is for the expansion argues that the current situation with Heathrow is hampering business.  Mr Johnson favours a new airport in the River Thames estuary, an idea related to by some as “Boris Island", as reported by the Daily Telegraph.

It is understood The Parliamentary Aviation Group has expressed its views for an increase in Heathrow’s capacity in some form.

Earlier this week, Cameron was asked if he was a ‘man or a mouse’ by Tim Yeo, green campaigner and senior Tory MP, over the issue with the PM not wanting to make a U-turn on policies.

It was the Culture Secretary, Jeremy Hunt, who defended Cameron by insisting he was a man and not a mouse. Mr Hunt, who opposes the expansion, has predicted the PM would however back an estuary airport.

He was quoted by The Independent saying: "It is plain the argument over aviation capacity is not going to vanish, you can't long grass this, it is necessary to come up with an answer.”

“Business needs an answer and I've no doubt the Prime Minister is going to provide one," he added.