David Cameron has attempted to defuse the row over a third runway at Heathrow Airport.

The Prime Minister said he would keep to his manifesto promise to block a new runway during this Parliament. However, he did not rule out the measure following the next general election in May 2015.

Labour MP John McDonnell, who has campaigned against the development, asked him to block a new runway while he led the Conservative Party.

Mr Cameron said: "While I do believe we need to establish a form of review that will bring parties together and make a decision about airport capacity, I will not be breaking my manifesto pledge."

The Prime Minister's comments echoed the sentiments of his deputy, Nick Clegg. The Liberal Democrat leader said: "The Coalition agreement could not have been clearer, we've ruled out giving the go-ahead to a third runway at Heathrow during this Parliament. It will not happen during this Parliament."

London Mayor Boris Johnson has claimed the decision to move Transport Secretary Justine Greening from her post in the Cabinet reshuffle signalled the Government's intention to give a new runway the green light.