Qantas will be split up and sold off at a "rock-bottom price" within four years if its proposed tie-up with Emirates goes ahead, the transport union says.
Flying kangaroo boss Alan Joyce announced on September 5 that his airline had inked a deal with Dubai-based Emirates which would see the two airlines sharing routes, frequent flyer programs, IT systems, airport facilities and other key parts of the businesses.
The tie-up, which replaces Qantas's close relationship with British Airways, is yet to receive the green light from the Australian Competition and Consumer Commission (ACCC), which is examining the proposal and has final approval.
But Transport Workers' Union (TWU) boss Tony Sheldon says the deal could lead to Qantas falling into foreign hands and ceasing to exist in its current format - and even risk national aviation security.
Mr Sheldon said Qantas had already sold its Adelaide-based catering business to Emirates, and he predicted more parts of the airline would be sold in coming years.
"I've no doubt in my mind whatsoever that the strategy that's been adopted by the present board and the CEO is a strategy that will mean the absolute demise and breakup of Qantas," Mr Sheldon said.
The TWU has put its arguments in a submission to the ACCC.
The commission has said it will take about six months to analyse the deal and make a decision whether or not to permit it.
Qantas has previously argued that its international operations are in decline and the deal with Emirates will help stabilise the business and be good for competition.
The domestic financial markets welcomed the deal, with Qantas's share price rising at least 10 per cent since it was announced.