Many residents are strongly opposed to Heathrow's expansion

The airport operator's move to include a new runway for short-haul flights at Heathrow onto a list of possibilities was described by one campaigner as "the mother of all U-turns".

John Stewart, chairman of Heathrow-based pressure group Hacan (Heathrow Association for the Control of Aircraft Noise) ClearSkies, said: "We feel betrayed and angry but equally as determined to fight on.

"This has to be the mother of all U-turns. For so long, BAA has reassured people that it would not be pressing for a third runway at Heathrow.

"But this doesn't mean the end of the line for the campaign. Although BAA are saying that they favour, at some stage, a third runway at Heathrow, public feeling is gaining momentum."

Air travel is set to increase sharply under the plans

His view has the backing of Dean Langley, vice-chairman of the No Third Runway Action Group and chairman of the village association for Harlington, Middlesex.

He told BBC News Online: "It disappoints me but does not surprise me.

"BAA has been sitting on the fence up until now. There are rumours circulating that they have been under pressure from the Government.

"There were a lot of people outraged by the proposals. The Government was the main recipient of that anger. I think they want to share that with BAA."

Magaret Cubley of the Council for Protection of Rural England said: "I feel betrayed really, especially living under the flight path at Maidenhead.

"When they gave the go-ahead for the new terminal, BAA gave a guarantee that there would not be a new runway - they've gone back on their word.

"How do we know this will be the end?" she said.

Business support

Meanwhile, the plans have met with a favourable response from the business community.

Frank Stroud, spokesman for the Thames Valley Chamber of Commerce, said: "Our view is supportive of a third short runway at Heathrow Airport as part of the growth of capacity in the south east of England.

"Our reason for that is that Heathrow Airport has been absolutely fundamental to the growth of economic activity across the Thames Valley.

"All of our members surveyed have said that they are here because of the proximity to Heathrow and to London and because of its communication links to the rest of the world."