Boris Johnson vows to block third runway at Heathrow

London Mayor Boris Johnson has insisted he will not allow a third runway to be built at Heathrow airport, amid reports the idea could be back on the table.

The government has previously ruled out a third runway, but reports suggest Chancellor George Osborne is pushing for the idea to be reconsidered.

One possibility is said to be an expansion and incorporation of RAF Northolt, six miles from Heathrow.

A consultation on UK aviation is due to report back in the summer.

In his Budget speech last week, Mr Osborne said the government "must confront the lack of airport capacity in south-east England".

Earlier, Prime Minister David Cameron said the UK must "retain our status as a key global hub for air travel" and he was "not blind to the need to increase airport capacity, particularly in the south east".

One of the options being considered is a new airport in the Thames Estuary - Mr Johnson's preferred choice.

The government is right to look at all new solutions for extra aviation capacity except the third runway at Heathrow”

The London mayor - who is currently campaigning for re-election - said a third runway at Heathrow would be "an environmental disaster".

"It would mean a huge increase in planes over London, and intolerable traffic and fumes in the west of the city - and it will not be built as long as I am mayor of London," he said.

"That is why the government is right to look at all new solutions for extra aviation capacity except the third runway at Heathrow. I look forward to engaging with [Transport Secretary] Justine Greening's consultation this summer."

The Independent on Sunday reported that Mr Osborne introduced Heathrow as an option for airport expansion at a cabinet meeting earlier this month - prompting anger from Deputy Prime Minister Nick Clegg and Ms Greening, whose Putney constituency is affected by aircraft noise.

The Free Enterprise Group of more than 30 Tory MPs has also called on the government to rethink its stance on Heathrow.

In a report earlier this year, they suggested compensating homeowners near the airport with up to £40,000, and also the idea of incorporating the runway at RAF Northolt and adapting it to take regular commercial aircraft.

They argued that other airports such as Amsterdam's Schiphol already use runways several miles from the control tower.

And earlier this month former Conservative environment minister - and chairman of the energy and climate change committee - Tim Yeo - also said the government should drop its opposition to a third runway at Heathrow.

He said new EU rules on aviation meant it would not lead to an increase in emissions.

The government could also choose to develop Gatwick, Stansted or Luton airports.

But when the coalition ruled out a third runway and sixth terminal at Heathrow in May 2010, airport operator BAA also withdrew its plans for a second runway at Stansted, and any expansion of Gatwick before 2019 has also been ruled out.

A spokeswoman for Ken Livingstone, Labour candidate for London mayor, said: "Reports that Boris Johnson's Tory government are considering this show the Tory Mayor's claims to have successfully lobbied against the third runway are hollow and that people who voted Conservative on this basis have been betrayed."