Twenty backbenchers had a private meeting with pilots and air traffic controllers before signing up to Keep Our Skies Safe, a pressure group to lobby the Government to stop the sale.
Some Labour MPs are making it clear that they would be prepared to vote against the Government if a Bill including the sell-off of the National Air Traffic Control System (Nats) is introduced in Parliament.
Despite public concern, deputy prime minister John Prescott is understood to be determined to press ahead with the sell-off of 51 per cent of the air traffic control system - which would net the Treasury pounds 1bn.
He is thought to have been "squared" by Chancellor Gordon Brown with a promise that the money would be used to fund key transport improvements Mr Prescott wants. "The thinking is that he cannot lose the Bill, because it is the only way he can fund his programme," a Westminster insider said.
In a reflection of growing disquiet over the issue, the Commons Transport Select Committee has already said it will order a safety inquiry if the part-privatisation plan goes ahead.
A recent poll conducted by the Institution of Professionals, Managers and Specialists found that eight out of 10 people believed that safety should be the prime concern in any changes to the ownership of Nats.
The new Chief Secretary to the Treasury Andrew Smith could again find his words at the 1994 Labour Party conference coming back to haunt him. Then, in Opposition, he told Labour Party members: "Our skies are not for sale."
There are further concerns about a new computer centre, currently being set up, which will not be fully operational until 2002. Some opponents of the proposed sell-off believe it should at least be postponed until after the new system is up and running.
Whitehall aides last night declined to confirm whether or not the measure will be contained in the Queen's Speech later this month.