HEATHROW AIRPORT will be able to sue the government for “potentially billions of pounds” if the third runway expansion “goes wrong,” MPs heard in the Commons yesterday.

Former transport secretary Justine Greening raised concerns that a clause in the Department for Transport’s agreement with airport bosses could mean the taxpayer will have to pick up a huge bill for costs.

Ms Greening quoted the document, which gives Heathrow Airport Limited (HAL) the right “to pursue any and all legal and equitable remedies” in the event an alternative scheme is preferred by the Transport Secretary or the government’s support is withdrawn.

She said: “The Secretary of State [Chris Grayling] himself said on Tuesday there are circumstances in which the runway could be built but not then used.

“Why was this term agreed to in the first place? Heathrow is a private company, it should therefore accept the risks.”

Transport Minister Jesse Norman — standing in for the absent Mr Grayling — told MPs that the phrasing was “standard” and that the government had taken advice from “distinguished leading counsel.”

He said however that there “might be some circumstance” in which Heathrow could take legal action — to cries of disbelief from the Labour benches.

Shadow transport minister Karl Turner described the statement as “a devastating revelation” and that it is “beyond belief that when this bombshell lands the Secretary of State is not here to respond.”

He added: “Isn’t it the case that the government has boxed itself into a corner by committing HAL to a risk-free investment and exposed itself to either massive cost recovery on the part of HAL or alternatively a crushing litigation before the decision has even been taken?”

Mr Norman claimed it was instead the “dampest of damp squibs” and repeated that “no indemnification has been given.”

In a statement the DfT later insisted that costs will not fall on the taxpayer and that Ms Greening’s point was “taken out of context” from a “non-legally binding document.”

The decision to go ahead with with an expansion plan was announced on Tuesday following years of debate.

It was met with strong opposition from both Labour and Tory MPs, as well as residents and environmental campaigners concerned about climate change emissions, noise and air pollution.

Trade unions Unite and GMB support an expansion of Heathrow for its claimed potential for an economic boost and job creation.