A total of four companies have been appointed to “assist in expanding” the airport about four months before the official government decision is announced, The Times reports.
It will ensure work on the new runway can begin as soon as possible in the event that the advice of the airports commission that recommends expanding Heathrow is followed, the airport said.
However, Heathrow Association for the Control of Aircraft Noise chairman John Stewart said the move was akin to “counting some very expensive chickens before they are hatched”.
He added: “All that we have heard is that Gatwick is still a viable option as far as ministers are concerned and Heathrow has been given no guarantees to justify this action.”