Miami: American Airlines boss Douglas Parker has pivoted from a spat with Gulf carriers that along with heads of other airlines from the United States he claims receive billions in state subsidies.

"The issue is not about airlines but governments," he told reporters in Miami on Tuesday.

Since January, Parker, the chairman and chief executive of one of the US' biggest carriers, has been part of a public lobbying campaign to freeze access to the Gulf carriers to the US. American, along with United and Delta, handed a 55-page document to their government this year that outlined claims of $42 billion in subsidies to Emirates, Etihad Airways and Qatar Airways over the past decade.

"We have evidence of subsidies that are so large and have such a potential impact on the US commercial aviation business ... [that] we could not ignore it and will not ignore it," Parker said.

But Parker also said that this is a "public policy issue" with the UAE and Qatar, which the US has open skies agreements with, not a campaign against his Gulf rivals. The agreement allows airlines from the UAE and Qatar to fly unrestricted to the US but Parker, and other US carriers, claim the subsidies that they say they receive breach the agreement.

On Monday, Parker told reporters at the International Air Transport Association (IATA) annual meet in Miami that the dispute "is not with" Emirates, Etihad or Qatar Airways.

Responding to these comments, Emirates airline President Tim Clark told reporters that Parker "could not be serious" in believing that the subsidy row was not personal.

Asked on Tuesday why the US carriers had singled out the Gulf carriers, Parker said the UAE and Qatar have "provided subsidies that have never been seen before."

The subsidy allegations against the Gulf carriers, which has been coined the open skies debate, threatened to overshadow this weeks largest annual airline executive meet, the IATA annual general meeting, that finished on Tuesday.

Qatar Airways Chief Executive Akbar Al Baker reportedly threatened to pull out of the oneworld alliance because of what fellow member American Airlines is doing. Etihad Airways President and Chief Executive James Hogan appeared on a panel on the first day and addressed the issue. But the heads of Delta and United, Richard Anderson and Jeff Smisek, only appeared at the closed door sessions and unlike the other executives did not front the media.