The airport says that 74% of 3000 adults polled in a survey support plans to increase capacity on its main runway and bring a standby runway into routine use for departing flights. It says that those interviewed live near the airport in Kent, Sussex and Surrey.

However, pressure group Communities Against Gatwick Noise & Emissions claims that the airport conducted surveys among departing passengers and says that exhibitions held to showcase the masterplan were held in urban areas not over flown by aircraft.

A spokesman for the group added: “It is absolutely appalling that Gatwick has released this poll result now when the consultation does not finish until 10 January. People will be even more confused by thinking that the consultation has finished already and that they do not have time to participate or object.”

A Gatwick spokesman dismissed the claims, saying that its recent survey was not taken inside the terminal, but was conducted by pollster YouGov of residents from Kent, Sussex and Surrey.

Other findings of Gatwick’s survey, published on Monday, show that three quarters of people support plans to safeguard land south of the airport in case it was ever needed for a new runway.

Gatwick Airport’s chief executive Stewart Wingate said: “These results show that an overwhelming majority of residents in Sussex, Surrey and Kent who were surveyed both support our plans for growth and recognise how important they are in terms securing the region’s economic prosperity and new jobs for generations to come.”

Polling was commissioned to gather views of local residents following publication of Gatwick’s draft expansion masterplan in October. The public consultation runs until 10 January.

 Photograph: Alastair Lloyd