A consultation was expected to report on whether work on the runway - which would be ready by 2020 - should begin this year.

But today transport secretary, Geoff Hoon said the decision had been delayed to allow proper consideration of the evidence.

In a statement to parliament, Hoon said: "The 2003 white paper made clear that given the economic benefits to the UK, the government supports the further development of Heathrow by adding a third runway and exploring the scope for making greater use of the existing runways, subject to meeting strict local conditions on air quality, noise and improving public transport access.

"I know that there are strong views across a range of interests," he said. "I will ensure that I give proper consideration to the evidence before me and will therefore take more time before making an announcement to the House, in January 2009."