David Cameron has delayed any decision on a controversial third runway at Heathrow until after the next General Election.

The Prime Minister is to set up a cross-party commission, chaired by ex-Financial Services Authority boss Sir Howard Davies, to look at the issue. But it is expected it will not report until after the 2015 Westminster elections.

However, political parties are still expected to make their views on the issue clear in their own manifestos.

The Tories pledged not to build a third runway in the run up to the last election.

But they are under increasing pressure from business and senior voices within their own party concerned that the UK will fall behind internationally if it does not increase airport capacity in south-east England.

However, London Mayor Boris Johnson – a fierce opponent – has again stepped up pressure on the Prime Minister to rule out such a move.

It followed Mr Cameron's demotion in the Cabinet reshuffle on Tuesday of Transport Secretary Justine Greening, whose Putney constituency is under the airport's flightpath and who was openly opposed to increasing capacity at Heathrow. Her replacement is not thought to have any such political baggage.

Mr Johnson said Ms Greening's loss of the portfolio signalled the Government's intention to give a new runway the green light. The Commission will be cross-party, something Labour has been calling for for a year.

Leader Ed Miliband is "sceptical" about the case for a third runway but is understood to be willing to co-operate with a review.