A consortium which failed in its effort to buy Australian airline Qantas has said it could return with another bid.
The takeover has faced strong opposition in Australia
Regulators rejected a last-ditch attempt by the group to get shareholder backing despite it saying it had garnered enough support to proceed.
Airline Partners Australia (APA) had earlier missed a key deadline in the bid process, scuppering its chances.
APA offered 10.8bn Australian dollars (£4.5bn; $8.9bn) for Qantas, despite opposition from some politicians.
The uncertainty over the bid has led to Qantas shares being suspended and calls from some shareholders for senior management to resign.
The consortium, which includes acquisitive Australian bank Macquarie and US private equity group Texas Pacific, had been set a deadline of 0900 GMT on Friday to win at least 50% of shareholder acceptances in order for the bid to go ahead.
Although APA failed to meet the deadline, a decision shortly afterwards by a key US investor to back the deal left the consortium with 50.6% of Qantas shareholder support.
APA sought permission to proceed with the next stage of the bid, in which it would be required to gain 70% of shareholder support over the next two weeks.
However, Australia's takeovers panel refused the request, saying it had "decided not to commence proceedings in relation to APA's application".
APA said it planned to challenge the ruling.
It added that it was "exploring a number of alternatives including the possibility of making a renewed offer for Qantas" at the same price.
The collapse of the bid prompted fierce criticism from some shareholders.
"It seems that the current board has crossed the line from representing shareholders to representing private equity," said investment adviser Marcus Padley.
Ministers said a new bid would have to subjected to the same regulatory scrutiny as the previous one, which was backed by the government despite misgivings by many politicians.
Qantas shares are expected to resume trading on Tuesday.