Qatar Airways chief executive Akbar Al Baker has threatened to leave the Oneworld alliance, accusing American Airlines of blocking his carrier's business in a major escalation of the subsidy row, said a report.

"If a major airline that invited us... to join the Oneworld is today restricting us from operating into that country... then I don't need to be part of this alliance," he told the BBC.

"I can do it alone," said Al Baker in an interview on the sidelines of the International Air Transport Association's annual meeting.

The threat comes hours after Al Baker also warned fellow airline executives at the IATA meeting about efforts to curb his airline's growth.

"Any rollback of liberal market access and open skies policies reverberate across the whole world and will lead to retaliatory protectionism," he said.

American Airlines chief executive Doug Parker meanwhile played down the issue. "Our dispute is not with any of those three airlines; we are just trying to get the U.S. government to enforce its trade policies," he added.