The Government had committed itself to making an announcement on Heathrow, including a third runway at the west London airport, before the end of this year.
But transport secretary Geoff Hoon said today that he would not make an announcement until January 2009.
The Government expressed support for expansion at Heathrow in its 2003 aviation White Paper and has since maintained its backing for a third runway.
But the Conservatives have come out against expansion and while big business and airlines favour a third runway, residents, local councils and conservationists are utterly opposed.
Mr Hoon added: "I know that there are strong views across a range of interests. 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."