Heathrow Airport has hired four contractors to work on plans to build a third runway at the west London airport, despite a lack of approval from the government.
Heathrow said today that Arup, CH2M, MACE and Turner & Townsend had been chosen to work on the expansion project.
"I'm delighted that our client partners are now on board and I look forward to working with them to give the UK a truly world-class, sustainable hub airport," said Heathrow director of procurement Ian Ballentine. "This privately financed, £16bn project will benefit the whole UK as we work to widen the supply-chain right across the nation."
The Airports Commission, led by Royal Bank of Scotland (RBS) chairman Sir Howard Davies, first recommended building a third runway at Heathrow last July. The government said in December that it would delay making a decision on airport expansion in the south east until at least this summer, saying "more work will be done on environmental impacts" in the interim.
Transport secretary Patrick McLoughlin refused to be drawn into confirming a date for the decision in an interview with the BBC this afternoon, saying only: "We've accepted the Davies conclusions. We're going to be looking at it."
International development secretary Justine Greening, a staunch opponent of Heathrow expansion, said over the weekend that she does not believe the government will back a third runway.
"I just don’t think it is a smart decision," Greening told the Telegraph. "Trying to expand Heathrow is like trying to build an eight bedroom mansion on the site of a terraced house. It is a hub airport that is just simply in the wrong place."