The Government is still intending to announce its decision on a third runway at Heathrow by the end of this month, Prime Minister Gordon Brown's spokesman has said.
The controversial proposal to expand London's busiest airport was the subject of a "brief" discussion at Cabinet amid reports that several senior minister harboured serious concerns about the plan.
The Government had been widely expected to give the project the green light this week, despite more than 40 backbenchers joining Opposition parties and environmentalist campaigners in demanding it be scrapped.
But the Prime Minister raised the prospect of a further delay on Monday night, when he agreed to meet rebel MPs for more talks.
Mr Brown's spokesman declined to say which ministers spoke in the Cabinet discussion, which he described as "constructive".
The Government has already taken a policy decision in principle in favour of additional capacity at Heathrow, subject to meeting conditions on air quality, noise and access.
Transport Secretary Geoff Hoon has the final decision on whether the project should go ahead and what form any expansion should take. He said shortly before Christmas that he would announce his decision in January, and Mr Brown's spokesman confirmed that this was still the Government's intention.
The hints at a delay came amid furious exchanges between supporters and opponents of the expansion.
Greenpeace said it had bought a section of land on the proposed site, and was planning to divide it into tiny pieces in a bid to gridlock the planning process with hundreds of legal challenges.
London Mayor Boris Johnson also insisted he would go to court over any decision to authorise the runway.
