The future of the air link between London and Belfast City airport cannot be guaranteed, the Northern Ireland Secretary has admitted.
Owen Paterson held talks with airline boss Willie Walsh in Westminster over fears the flight to and from Heathrow could be axed following the expected takeover of BMI by BA's parent company IAG.
Mr Paterson told the Northern Ireland Affairs Committee that legal checks were still being carried out ahead of the completion of the deal.
Asked if he could guarantee the route's future, he said: "I'm in no position to guarantee anything because when I saw him (Mr Walsh) on Friday evening he was still going through due diligence. This is all commercially sensitive. They are in the early stage of investigation, some other airline might come in a buy it. It might break up and disappear, sadly."
Mr Paterson said he "stressed" to Mr Walsh, the head of IAG, during a meeting at the Northern Ireland Office in London the "vital" importance of the air link.
He added: "I made it clear we think this is of great importance. He made it clear that it fitted in with the British Airways system of maintaining regional spokes going in to a central hub feeding long-haul flights. It seemed to me that our interests coalesce.
"But this is a commercial decision, we can't interfere in how this turns out. All we can do is keep a close eye and keep in close touch, which is exactly what I have agreed with Willie Walsh."
IAG, which also runs Spanish carrier Iberia, intends to concentrate on BMI's long-haul routes out of London.
Low-fare carrier bmibaby started in 2002 and flies out of Belfast, Birmingham and East Midlands airports.
Independent MP Lady Sylvia Hermon said the lack of assurances over the route's future were "deeply worrying and concerning".