The Liberal Democrats could be set to change their position on airport expansion in the south east of England.
The party has previously backed a complete ban on the construction of any new runways in the UK but two Lib Dem MPs have now tabled an amendment that would allow Gatwick airport to be exempt.
Solihull MP Lorely Burt and St Austell and Newquay MP Stephen Gilbert have put forward the amendment which is set to be debated today at the party’s annual conference in Glasgow.
The Lib Dems' "pre manifesto" for next year's general election, published last month, said: "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".
This follows its last general election manifesto which promised to "cancel plans for a third runway at Heathrow and other airport expansion in the South East."
However, according to The BBC sources close to Liberal Democrat leader Nick Clegg are suggesting that airport expansion could take place without increasing carbon emissions due to technological advances.
This follows the backing of expansion at Gatwick by business secretary Vince Cable, who told the conference on Sunday it was a “preferable alternative” and “less problematic” than Heathrow.
Last week Liberal Democrat leader Nick Clegg hinted he wanted to end the party’s outright ban on new runways. “I do happen to think the environmental impact can... be consistent with some form of airport expansion, given the rapid improvement in environmental performance of modern aircraft,” he told The Times.
The energy and climate change secretary also came out in support of Gatwick: “We have shown in government that you can have greener energy and still have affordable energy, that you can have growth and it can be green, that you can have cars but it can be zero-carbon cars,” Davey told the BBC Radio 4’s Today programme.
“If you look at the future of flight it is possible to imagine, with technological innovation, that we have zero-carbon flight in the future. It is not a U-turn on environmental criteria.”
He added: “If those criteria can be met elsewhere they clearly cannot be met at Heathrow. We are not against flying, we are not against people using their cars, we are not against people enjoying life. We just want people to do it in a low-carbon way.”
Both Heathrow and Gatwick airports have been shortlisted for potential new runways by the Airports Commission which will be making its final recommendation for expansion in the south-east in summer 2015 after the next general election.
A new airport in the Thames Estuary - supported by London Mayor Boris Johnson – was last month ruled out by the Commission.