The Liberal Democrats are opposed to runway expansion at any airport in the UK, according to their election manifesto.
The party, headed by Deputy Prime Minister Nick Clegg, wants to ensure "no net increase in runways across the UK" for environmental reasons.
It is against airport expansion, in the south-east in particular, due to pollution.
However, Chief Secretary to the Treasury Danny Alexander last week refused to confirm the Lib Dems will commit to this policy should the party again be part of a coalition government after next month's election.
The Lib Dem manifesto reads: "We will carefully consider the conclusions of the Davies Review into runway capacity and develop a strategic airports policy for the whole of the UK in the light of those recommendations and advice from the Committee on Climate Change.
"We remain opposed to any expansion of Heathrow, Stansted or Gatwick and any new airport in the Thames Estuary, because of local issues of air and noise pollution.
"We will ensure no net increase in runways across the UK."
In January, Easyjet threw its support behind London Heathrow's plan for a third runway (see news, January 30). The news was a blow to Gatwick, which has been campaigning for a second runway and is Easyjet's biggest base.
Graham Smith
