Mayor of London Boris Johnson is pressing ahead with plans for an off-shore airport near Sheppey.

Last week’s Times Guardian reported the Thames Estuary Steering Group, an expert panel appointed by Mr Johnson, put forward the idea of using high-tech flood defences in the form of man-made islands as runways.

Their report said an off-shore scheme - dubbed Boris Island - should be considered because of problems extending existing airports and developing regional ones.

Sheppey MP Gordon Henderson was dismissive and said Prime Minister David Cameron would not support it.

But a seminar at City Hall today heard the UK economy will suffer and London will lose jobs to European competitors unless a new hub airport is created in the south east.

While Dan Moylan, deputy chairman of Transport for London who prepared the report, said the seminar was not about deciding a location, Mr Johnson reaffirmed his opposition to expanding Heathrow and confirmed he wants an off-shore airport to be considered.

He said: “We need to start planning for a brand new airport that can help meet the ever increasing demand for aviation.

“We should certainly look at the Thames estuary where the regeneration benefits would be great.”

The Mayor met business leaders from the services sector and aviation industry who welcomed the Government’s review of aviation policy but called for greater urgency in recognising the economic needs of the capital and the central role aviation plays.

He said more capacity is needed to support new air links to the growing economies of China, India and South America.

Mr Moylan said: “Extra capacity at a hub airport is crucial if we are to support the rebalancing of the UK economy, which this government seeks, while remaining consistent with the Mayor’s goals of improving the quality of life of all Londoners and reducing transport’s contribution to climate change.”

A further report will be published later this year which will present options, including a range of locations for new airport capacity, such as a new airport possibly in the Thames Estuary, as well as consideration of existing sites with the exception of Heathrow.

The RSPB has again dismissed the expensive campaign for an international airport hub in the Thames estuary.

Much of the estuary has international environmental protection, safeguarding its immense importance for native and migratory birds, rare plants and habitats. Hundreds of thousands of birds use the estuary as a major migratory route, posing a considerable threat to planes from bird strike.

Chris Corrigan, the RSPB’s Director for South East England said: “Boris continues to pursue this pipe dream, but no amount of wishful thinking on his behalf changes the fact that the Thames Estuary is not dead space waiting for development.

"It is home to an immense number of birds and other wildlife. You cannot recreate the estuary nor move the native or migratory wildlife that relies on it for food and shelter.

“I’m sure the Mayor doesn’t want to go down in history as the man who decimated not just birds in the Thames, but global species too, while putting air passengers’ lives at risk due to bird strike.

"I’d urge him to drop this costly pursuit now and look to further strengthening, greening and improving London’s public transport systems."