London mayor Boris Johnson argues case for new airport
London mayor Boris Johnson has outlined the economic case for a new hub airport in the south-east of England.
Making a speech to business leaders and representatives of the aviation industry, he said the constrictions of Heathrow Airport were becoming "ever more apparent and ever more damaging".
A £50bn plan for the Thames Estuary has been put forward to increase flight capacity without expanding Heathrow.
But there is opposition to the scheme on environmental and economic grounds.
Mr Johnson said: "As the world economy changes and global power shifts to the East, the constrictions of London's hub airport are becoming ever more apparent and ever more damaging."
He added that in the next 15 years 75 million Chinese households would enter the middle classes - a "phenomenal market".
But, he said, their business is "already being snaffled up by our friends on the continent who chortle at our continued inertia".
He warned that to do nothing would lead to "economic stagnation".
Passenger demand for London's airports is forecast to increase from 140 million passengers a year in 2010 to 400 million passengers a year by 2050, according to a report by the Greater London Authority.
But when the plan to build a facility between the Essex and Kent coasts was debated in October, concerns were raised about damage to the environment.
The RSPB, Medway Council and Kent County Council have opposed the idea, saying it is "undeliverable, unaffordable and unnecessary".
They have launched a campaign website where they say people can email the mayor directly.
Ryanair boss Michael O'Leary is among those who have criticised the financial case for the transport hub, saying that London needs more runways at the existing airports rather than a new one.
Mr O'Leary said: "I think it's absolutely nuts, there's no requirement for any new hub airport."
In May last year plans for a third runway and sixth terminal at Heathrow were scrapped when the coalition government took office.