Campaigners claim a new town the size of Crawley will have to be built from scratch if a second runway is allowed at Gatwick.
The Gatwick Area Conservation Campaign (GACC) says it would create 25,000 new jobs, and a town of around 100,000 people would be needed.
Brendon Sewill, chairman of GACC, said: "If a second runway is built it will urbanise and change the character of much of the countryside in Sussex and Surrey.
"By increasing hugely the volume of traffic and the number of houses, people in much of Sussex and Surrey could no longer say they live in the country."
The warning comes as Gatwick prepares to publish its Master Plan, detailing how it will remain a viable business and increase capacity.
Sussex Enterprise, representing four-fifths of businesses, is campaigning in favour of the second runway.
Communications director Steven Gauge said: "There has been a great deal of scaremongering around this issue and very unrealistic figures have been thrown around.
"Without a second runway some businesses may choose to relocate away from Sussex.
"Our research has shown that jobs and people could be lost."
Anti-runway campaigners are angry about the extra air pollution a second runway could cause.
Under the Government's plans, a second runway will be built at Gatwick if the suburbs surrounding Heathrow are ruled too polluted for further expansion.
Mr Sewill said: "It will affect fewer people but it is still extremely nasty for the people it does affect. People living around Gatwick expect to live in the country."
Friday March 4, 2005
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