A final decision on whether to build a new runway at Heathrow Airport has been put off until at least next summer.
After discussion of the controversial issue by Prime Minister David Cameron and senior Cabinet ministers, Transport Secretary Patrick McLoughlin said there was a "clear" case for airport expansion "but it's vitally important we get the decision right so that it will benefit generations to come".
He said ministers - who had promised a decision by the end of the year - would "undertake more work on environmental impacts, including air quality, noise and carbon" and "continue work on all the shortlisted locations" - two at Heathrow and one at Gatwick.
The Davies Commission concluded in July that a third runway at Heathrow was the best option - if a string of measures were put in place to deal with noise and pollution - but left open the option of expanding capacity at Gatwick instead.
Critics say the delay will harm the economy and is a politically-inspired move to avoid damaging resignations by high-profile Tories - including London mayoral candidate Zac Goldsmith, who has vowed to quit as an MP if Heathrow is approved.