Under plans to privatise the service, employees are to be allocated 6 per cent of the shares.
The Chancellor will sell 51 per cent of Nats, which is will be worth, at a conservative estimate, pounds 500 million on flotation. The Government will keep 49 per cent, and 45 per cent will go to a new private sector partner, leaving the employees controlling the key balancing tranche of 6 per cent of the shares.
Ministers insist that the move is to reassure the workforce that they have power as shareholders, but it was seen at Westminster as an attempt to buy them off.
Gwyneth Dunwoody, the formidable Labour chairman of the Commons Select Committee on Transport, told The Independent:
"They are hoping that people will take the money because they are human beings, but I don't think they will be bought off. The employees see themselves as a public service."
John Prescott, the Deputy Prime Minister, will make it clear that safety will be the priority, and a safety watchdog will be established to operate independently of Nats.
But the Government has been warned that it will face sustained opposition from Labour MPs if it goes ahead with the sale, as expected, with a Bill in the next Queen's Speech.
Addressing a meeting of air traffic control officers, the former Labour transport minister Gavin Strang warned that the plan would not prove popular with voters.
Mr Strang told members of the IPMS union that it was coming at a bad time for the industry. The select committee on transport warned on Wednesday that control tower staff were finding it increasingly difficult to cope. Staff had registered "overloads" at the key West Drayton centre on 49 occasions last year, more than double the 24 reported in 1997.
He asserted that the sale need not be a fait accompli. He said there was a strong argument that Nats should be restructured as a publicly owned company allowed to borrow on the private money market.
"The priority for air traffic control must be safety. But privatisation was ... considered attractive for financial reasons."
Mr Strang was a member of the Cabinet when the proposals were being finalised.
"Safety should be the overriding criteria against which all policies are judged," he told the controllers.
He pointed out that the service was vital for national security and that in an emergency the military needed "immediate and unqualified control".
Security was undoubtedly one reason why no other government had a privatisation strategy in the sector.
He said the sell-off process would divert management time when the focus should be on the new air traffic control centre for southern England. The starting date for the En Route Centre, at Swanwick, had been postponed from 1996 to 2002, he pointed out. To retain the maximum financial benefit from the partial sale of Nats, ministers should wait for the establishment of Swanwick.
He argued that, unlike with other state sell-offs, the decision had not been made to avoid a financial drain or introduce competition: Nats was self-financing and made an operating profit.