THE Mayor of London Boris Johnson has said on television he does “not want to build an airport in the Thames Estuary”.

Mr Johnson has previously proposed building a £40bn airport dubbed Boris Island as an alternative to having a third runway at Heathrow.

But on BBC’s Question Time last night, the Mayor was accused by host David Dimbleby of undercutting Conservative Party leader David Cameron by going against Tory policy, which does not support building the airport.

Mr Johnson said: “That is complete codswallop. I dispute every single one of your assertions. I don't want to build an airport in the Thames Estuary.”

However a statement issued by the Mayor’s office today says building the airport has not been ruled out.

A spokesman said: “The Mayor was referring to the fact that there are no actual plans in place to build an airport.

“However he believes the complex and critical decisions on Britain's aviation future require mature exploration of every possible option.

“He has set up a steering group whose role is to oversee further study and research on issues in the estuary such as energy, flood management, transport, ecology and regeneration.

“Their research will be invaluable when deciding if a new airport there could meet London's future needs.”

Mr Johnson’s proposal has faced mounting opposition from groups including Dartford Council, Medway Council and Kent County Council as well as the RSPB, as the airport would fall within a hub for hundreds of thousands of migrant birds.

The Board of Airline Representatives UK, which represents more than 90 airlines including British Airways, Air France and Virgin Atlantic, is the latest group to oppose the project.

Chief executive of the board Mike Carrivick said: “We're not objecting to the construction of an airport, but it's in the wrong place, it's as simple as that.

“It's in a transport cul-de-sac. The whole market place which uses it has to approach from one side.

“It's got to be understood any airport has immense infrastructure for freight, hotels, passenger handling.

“It will impact on towns, businesses, local roads, motorways, railways and schools.”

Mr Carrivick also warned against the threat of bird strikes after a US Airways plane crash landed on the Hudson river in New York.

The plane was believed to have been struck by birds.