The Labour leadership is gearing up to vote against plans for a third runway at Heathrow.

Such a move would raise fresh uncertainty over expansion of the London hub.

Senior figures in Labour leader Jeremy Corbyn’s camp have told the Financial Times that he and his high-ranking colleagues are almost certain to oppose Heathrow’s third runway proposal when it comes to a Commons vote.

“It has to pass our tests and no one here expects that to be likely,” said one ally of Corbyn, referring to several environmental hurdles listed in Labour’s election manifesto.

Another senior Labour figure told the newspaper: “If the vote is any time soon there is no way we would back it, mainly on the basis of air quality, and that’s unlikely to change any time soon.”

Labour fought the general election in June on a manifesto that appeared to give a lukewarm blessing to the proposed £16.5 billion expansion of the UK’s biggest airport.

But the manifesto wording suggested that Labour would need to be satisfied of certain conditions being met if it were to back the contentious scheme at Heathrow.

While recognising the need for “additional airport capacity” in the south-east of England, the manifesto indicated Heathrow’s third runway would have to comply with several tests.

These would involve “noise issues to be addressed, air quality to be protected, the UK’s climate change obligations met and growth across the country supported”, said the Labour document.

Prime minister Theresa May backed a third runway at Heathrow last October, but the Conservatives lost their Commons majority at the general election in June.

Government officials said after the election that there would be a Commons vote on Heathrow expansion, which is expected to take place in the first half of next year.

Corbyn has always had reservations about Heathrow’s expansion, while his closest political ally, shadow chancellor John McDonnell, is an opponent of the scheme. His constituency is close to Heathrow.

The Labour leadership is refusing to say whether or not it would try to whip its MPs against the third runway plans, or allow them a free vote.

Corbyn has acknowledged that there is a “huge debate in the party” about Heathrow expansion, and his spokesman said: “We will assess any proposals against our four tests.”

Lord Adonis, the former Labour transport secretary who now heads the government’s National Infrastructure Commission, believes the Heathrow project could fall foul of political instability given May’s lack of a working majority in the Commons.

But he said that he would be “very disappointed” if Corbyn opposed the third runway plans.

“This isn’t just a project for London,” he told the FT. “It would provide improved links to regional airports which desperately need better connectivity with the rest of the UK, as well as internationally.”

Supporters of expanding Heathrow argue that it is the best-placed UK airport to offer more long-haul flights, in a move that could boost the British economy by improving links with other countries, notably in emerging markets.

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