Britain must confront the lack of airport capacity in the south east, says Chancellor

"We cannot risk cutting ourselves off from the rest of the world," said Osborne. The Transport Secretary will set out the Government’s thoughts on the issue “later this summer,” he said.

Planning law expert Jon Riley of Pinsent Masons, the law firm behind Out-Law.com, said that the Government looks set to perform a u-turn on airport capacity.

"Taken with the Prime Minister's speech on Monday, it seems the Government are taxiing for a u-turn on south east airport capacity," said Riley. "The language of confrontation suggests one or more new runways will be supported in next week's launch of the aviation framework - then the debate begins as to where they should be built - Heathrow, Boris Island or elsewhere."

"This is about connecting the whole nation to the world, not just London, so it's important we hear strong regional voices in the debate to come," said Riley.

"The Government has blocked plans for a proposed third runway at Heathrow since it took office in 2009, a decision which business group London First branded as “negligent” in a report (90-page / 2.3MB PDF), which called for “significant improvement” to the capital’s transport links.

Passenger demand for London's airports is forecast to increase from 140 million a year in 2010 to 400 million passengers a year by 2050, according to a previous report by the Greater London Authority.

Transport Secretary Justine Greening is expected to publish the Government's aviation framework for consultation early next week, which will consider the options to increase airport capacity.