Jeremy Corbyn has signalled that Labour could scrap Heathrow expansion if it gains power.

The intervention came as Transport Secretary Chris Grayling said he is “cautiously optimistic” that MPs will back the controversial third runway project.

And Foreign Secretary, and anti-expansion campaigner, Boris Johnson drew criticism for being out of the country and missing the crunch Commons vote on the issue on Monday.

Asked if Labour could halt Heathrow expansion if it gets into government, Mr Corbyn said: “It depends what stage the whole thing has got to by then.

“We would look very carefully at airport capacity all across the South East because there is under-used capacity at both Luton and Stansted, and there is a need, I think, to up the usage of Birmingham and other airports.

“And Manchester is developing as a hub as well. Not everybody wants to fly to London in order to fly out of London.”

Jeremy Corbyn
Jeremy Corbyn has suggested a Labour Government could block a third runway (Kirsty O’Connor/PA)

Labour is officially opposed to the expansion but Mr Corbyn has allowed MPs a free vote on a measure that is supported by trade unions like Unite but opposed by the shadow chancellor John McDonnell.

Mr McDonnell, whose Hayes and Harlington constituency is directly impacted by the expansion plans, told the BBC: “Whatever happens in Parliament today, if we lose in Parliament we’ll be in the courts.

“The boroughs will challenge it, as will the London mayor. And there will be continuing direct action campaigns.

“My view is that we have got to block it because it is so dangerous for climate change issues.

“This a threat not just to my community, this is a threat to the whole country and the planet.

“If we don’t stop this we cannot be taken seriously on climate change.”

Heathrow: options for new runway

MPs will decide on Monday evening whether to approve the expansion of Europe’s busiest airport, as more than 40 Labour members said they would go against party policy and support the Government’s decision.

Mr Grayling told BBC Radio 4’s Today programme he was hopeful the plan would be approved by MPs.

“I’m cautiously optimistic, it’s never over until it’s over and the vote actually happens but there is strong support across the political spectrum on this,” he said.

“It’s not usual for me to find myself campaigning on the same side as Len McCluskey of Unite but he is right in arguing that this is a project that can make a real difference to Britain, to jobs, to connections around the world and indeed to the whole UK because this is not simply a project for London and the south-east, the connections that we create through Heathrow benefit every part of the UK.”

He added that it was “very clearly a private sector project” and “the taxpayer is not going to be paying for the expansion of Heathrow Airport”.

Ahead of the vote, officials said the expansion of Heathrow would create 114,000 extra jobs in the area around the airport by 2030, with an extra 16 million long-haul seats by 2040.

It would represent the first full-length runway in the south east since the Second World War, the Department for Transport said.

AIR Heathrow

Among Labour MPs who have signed a pro-expansion letter are many leadership critics, including Luciana Berger, John Mann, Mike Gapes and Wes Streeting, who argue it is right to back a scheme that will create jobs and growth.

Opponents have attacked the scheme on environmental, noise and financial grounds grounds, with Friends of the Earth saying it was “morally reprehensible” and would see the enlarged Heathrow emitting as much carbon as the whole of Portugal.

A plane flies over Heathrow
The scheme has been opposed over environmental and noise concerns (Steve Parsons/PA)

Paul McGuinness, chairman of the No 3rd Runway Coalition, said: “Heathrow expansion will be bad for London and bad for Britain.”

The Foreign Secretary is in Afghanistan for talks with senior government officials, the Afghan Ministry of Foreign Affairs has said.

Mr Johnson once said he would lie down in front of bulldozers to prevent construction of the £14 billion runway.

The Foreign Secretary defended his decision to miss the crucial Commons vote, saying his resignation from the Government would achieve “absolutely nothing”.

In an open letter to constituents in his Uxbridge and South Ruislip seat, quoted in the Evening Standard, Mr Johnson also suggested the third runway may never happen.

Councils impacted by Heathrow expansion plans say they will seek a judicial review if Parliament backs the project.

The leaders of Wandsworth, Richmond, Hillingdon, and Hammersmith and Fulham councils have joined forces to try and block the third runway initiative if MPs give it the go-ahead.

Richmond Council leader Cllr Gareth Roberts said: “We will fight this proposal through the courts and we will win because the alternative is to condemn thousands of people to premature deaths from dangerous levels of air pollution.”