“So this is not a one-off deal or any kind of special arrangement with Heathrow itself.”

That’s what transport minister, Jesse Norman, told the Commons yesterday, after ministers finally approved plans for a third runway at Heathrow. But opponents of the runway say he may have misled parliament.

Experts have been saying for decades that southeast England needs more airport capacity, but the question of where the expansion should take place has been the subject of bitter disagreement.

Former Conservative minister Justine Greening has been an outspoken critic of the campaign for a third runway at Heathrow. The west London airport’s flightpath goes right over her Putney constituency.

On Thursday, she accused the government of giving Heathrow Airport Limited – the company in charge of the third runway project – preferential treatment over rival bidders, Gatwick Airport and Heathrow Hub Limited, who wanted to extend the existing runway.

The government has an agreement with Heathrow Airport Limited which contains a clause reaffirming the company’s right to sue the government if ministers back out of the scheme.

Yesterday, the transport minister told parliament that “versions of the same document were also agreed” with Gatwick and Heathrow Hub.

But as FactCheck reported, the Department for Transport would not let us see the documents that would show whether the cost recovery clause was only agreed with Heathrow Airport Limited, or whether it had been offered to Gatwick and Heathrow Hub too. It said the documents were too commercially sensitive to be released.

However, within hours of publishing our article, Heathrow Hub got in touch. They showed us the agreement they made with the government. It does not contain any clause reaffirming the company’s rights to sue the government if they back out of the deal.

This could put the transport minister’s statement that the Heathrow Airport Limited clause was not part of a “one-off deal or any kind of special arrangement” in a new light.

It now looks like there was at least one difference between the agreements drawn up with the two Heathrow projects. (Gatwick Airport Limited said they couldn’t share their agreement with us because of confidentiality clauses.)

Ms Greening told FactCheck: “As Heathrow Hub have confirmed they had no such cost recovery clause, it’s clear [Department for Transport] ministers should correct the parliamentary record to avoid any possibility of misleading parliament.

“I’m sure they’ll want to set the record straight that this was indeed a special clause that only Heathrow Airport Limited had.”

A DfT spokesperson said: “The government has been clear that expansion and Heathrow would be privately financed and the costs will not fall on the taxpayer.

“The accusation of potential financial liability has been taken out of context from a non-legally binding document, which makes clear that it gives Heathrow no legal right to any costs or losses from government should their scheme not proceed.

“As set out by the minister yesterday, the Statement of Principles agreed with each promoter had substantially the same form. There were of course differences to reflect the unique commercial perspectives of respective parties and their individual scheme designs.”