by political editor Paul Francis

Boris Johnson has renewed his call for a new Thames Estuary airport - indicating he will use his second term in office to continue to push the idea.

Urging the government to give the scheme its backing, he repeated his belief that the hub airport - dubbed Boris Island - had the potential to place London as the "economic powerhouse of Europe."

His comments will dismay opponents of the scheme, who insist the idea is a non-starter and argue that it is not supported by the aviation industry.

In a newspaper interview, Mr Johnson called for a four-runway airport, which would be the biggest in the world, to be built in the Thames Estuary.

He said: "The Government has got to seize the nettle. This is a moment for greatness. It is a moment for bravery.

"I've said my piece on this. I can't say any more. People know what I think, they know where I stand."

A cross-section of Lord Foster's plans for a new Thames Estuary airpor

Mr Johnson went on: "My gut feeling is that you could entrench London's position as the economic powerhouse of Europe.

"You would solve all sorts of problems in transport infrastructure and regeneration if you went for a big, bold solution of the kind that Norman Foster was outlining.

"If the Coalition were to go for something like that it would be an incredible expression of confidence in UKPLC, in the dynamism of this country.

"I am not so naive as to think that that can be done without huge political opposition."

He acknowledged the government was yet to be committed.

Mr Johnson said: "I would say that the Government is yet to be persuaded. That doesn't mean they are incapable of being persuaded, but they are yet to be persuaded."

The government has said it will consider the option in a review of aviation capacity.