A NATIONAL poll found most respondents oppose an international airport being built in the Thames Estuary.
The survey, carried out by market research firm ICM on behalf of Medway Council – which is against the proposals – asked 1,000 people across the UK their opinion on the issue.
Mayor of London Boris Johnson has backed the scheme, in which Heathrow would be replaced as the main flight destination into the capital, at an estimated cost of £70billion.
Opponents say the scheme is unnecessary and would have a detrimental impact on wildlife.
The poll, carried out on August 19, 20 and 21, asked 1,000 randomly-selected adults whether London needed another airport, whether £70 billion was too much to spend, and if Manston in Thanet and Birmingham should take on extra capacity.
More than three-quarters said a new airport was not needed, 81 per cent said it was too expensive, and nine out of ten said existing airports should be expanded to cope with expected demand.
Kent County Council has joined with Medway Council and the RSPB in opposition to the scheme.
Medway Council leader Cllr Rodney Chambers said: "This national survey shows that Boris Johnson is flying in the face of public opinion with his plan for an estuary airport.
"It is a proposal that has already been dismissed by the airline industry and by the Government, and this poll makes clear that no one at all sees it as a serious option.
"A Thames Estuary airport would blight huge parts of Kent and Medway, as it would need a huge amount of infrastructure to support it, and it would devastate one of Europe's most important areas for migrating wildfowl.
"An overwhelming majority of people agree it is unaffordable to spend up to £70billion on a new airport, and that improving regional airports is the right policy. Boris needs to admit it is a pie-in-the-sky idea and drop it for good."
Mr Johnson, who is seeking re-election in May and is chairman of Transport for London, has said reclaiming estuary land for runways was the most sensible solution.
His spokesman said: "London is the motor of the UK economy, and if it is to retain its position as the heartbeat of global business then a new hub airport is an absolute necessity."