Anti-noise campaigners have warned local residents that the proposal to add a third runway at Heathrow airport, using a smaller runway alongside the existing southern runway, was a real option and would result in planes following a new flight path over the borough.

A third close parallel runway could be built within the confines of Heathrow avoiding the need to knock down houses and villages, which the option to build another runway to the north of the airport would necessitate.

The protesters fear that this would be far less damaging from a public relations point of view and could be offered as a compromise where the aviation industry say that they have listened and therefore only build a shorter runway which does not destroy people's homes.

The option of a third runway, either north of the airport or a close parallel one to the southern runway, is an unacceptable plan for campaigners who have protested against Heathrow expansion for many years.

Philippa Edmunds, one of the campaigners who took the government to the European court of Human Rights last year and won, wants to ensure that local people are aware of the close parallel runway option for the southern runway.

She said: "This option means that big planes could stay on the existing runways and the new one could take the smaller planes and ease the capacity problems that way. A close parallel runway could necessitate knocking down some buildings within the airport but that would be feasible and worthwhile as the aviation industry would get its extra Heathrow runway. But a runway is a runway and would be very noisy whatever length it is.

"People in the industry have known that this close parallel runway option has been viable for years but kept quiet about it before T5 was agreed."

"Buildings within the airport can easily be rebuilt and this course would be an easier approach to sell to the public than the site to the north of the airport which involves destroying several villages and 4,000 homes.

Chairman, John Stewart of Hacan ClearSkies, the campaign group for the control of aircraft noise, believes the close parallel runway is a real option.

He said: "The option for a full scale new runway which would see the destruction of around 5,000 houses would be politically very difficult for any government. The short parallel runway is a real option. We believe BA probably favours it.

"We want them to spell out exactly where the new flight path would be. It is no good having a small and cuddly runway when swathes of people in the borough of Richmond could be newly affected by aircraft noise."

A consultation exercise will start in the spring about the possibility of runway expansion at Heathrow.

A spokesman from British Airport Authority said that it was the government's decision where to put the extra runway for the south east of England.

A spokesman from the Department of Transport and Local Government and the Regions said: "We will be issuing a consultation document offering options for the country's aviation infrastructure this spring.

A BA spokesman said: "We believe there must be infrastructure investment in the South East so it can continue to grow as a world class trading centre. Without more investment there would be higher prices, more delays and less choice.

"Ultimately it will be the decision of the government for any future expansion. We believe any expansion should be under strict environmental conditions."