A third runway at Gatwick is included in all the plans submitted by three groups bidding to take over the running of the West Sussex airport, it has emerged.

Local residents have vowed to oppose any expansion of the airport and an existing legal agreement means no runway can be built there before 2019.

But despite this, Manchester Airport Group, Global Infrastructure Partners and a third bidder all plan to build the extra runway.

The deadline for bids to take over the airport, being sold by airport operator BAA, is next Monday, April 27.

The Gatwick Area Conservation Campaign group said today: "There is no physical space for a new runway between the towns of Horley and Crawley.

"If the pressure of public opposition defeats the Stansted and Heathrow proposals, there are good reasons to suppose that the opposition would be even more fierce from the articulate and environmentally conscious population around Gatwick."

Shadow transport secretary Theresa Villiers said today: "Conservatives oppose a second runway at Gatwick. If we are elected to Government, we will not allow a second runway to be built at Gatwick."

The Government has given the go-ahead to a third runway at Heathrow and there are also plans for a second runway at Stansted.

The Government's 2003 aviation White Paper did include options for runway expansion at Gatwick, but added that - due to the agreement signed in 1979 between BAA and West Sussex County Council - no new runway could be constructed before 2019.

BAA had decided to sell Gatwick before it was ordered earlier this year by the Competition Commission to dispose of the West Sussex airport and also to sell Stansted.

Liberal Democrat transport spokesman Norman Baker said: "These expansion plans are pie in the sky. If these firms are bidding on the basis of a second runway at Gatwick, they can think again. There will be enormous opposition locally for air quality reasons and nationally for environmental reasons.

"Does the airline industry not realise the urgency of the need to combat climate change?”