The lobbying group that represents American (AAL) - Get American Airlines Group, Inc. Report , Delta (DAL) - Get Delta Air Lines, Inc. Report and United (UAL) - Get United Airlines Holdings, Inc. Report and their labor unions said it has found additional evidence of subsidies to Qatar Airways by the Qatar government.

"Forensic investigators have uncovered a financial statement in Singapore for Qatar Airways that indicates that the government of Qatar provided close to $7 billion into the company in 2014," the Partnership for Open and Fair Skies said Wednesday in a prepared statement.

"This enormous subsidy is in addition to the $17 billion Qatar Airways had already received from its state owner in the past decade, bringing the total amount of known subsidies and other benefits that the three Gulf carriers have received to nearly $50 billion," the partnership said.

"The discovery of additional subsidies directly contradicts information that Qatar Airways submitted to the United States government, as well as public claims by CEO Akbar al Baker," the group said. "Qatar Airways has long refused to release its full compendium of financial documents and this state-sponsored subsidy, like many others, was omitted from the official filing submitted to the U.S. government's public docket."

A spokesman for Qatar didn't immediately respond to an email or a phone call. Jill Zuckman, spokeswoman for Open and Fair Skies, declined to provide additional details regarding the financial statement in Singapore.

At a press conference in Los Angeles in January, when Qatar announced new service to LAX, "Al Baker hit back hard at those {subsidy} claims, pointing out subsidies that the US3 have allegedly received from their own federal and state governments, including discharge of debts and pensions through the federal bankruptcy process, fuel subsidies, tax breaks, and government bailouts," according to a report in AirlineReporter, a Seattle-based trade publication.

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"Al Baker also suggested that the unfair competition claims were a red herring, asserting that the US3 have swindled the American flying public with high fares, low seat count, and bad service and products," AirlineReporter said.

In a January 2015 report prepared for American, Delta and United, investigators and accountants cited evidence of $42 billion in subsidies to the three Middle East carriers -- Emirates, Etihad and Qatar -- by the governments of the United Arab Emirates and Qatar.

The report's release was the first step in a lobbying campaign intended to convince the State Department to seek to curtail a business model in which the three carriers expand rapidly in the U.S., benefitting from subsidies that are not permitted by the Open Skies treaties which enable the expansion.

On Friday, the State Department informed representatives from American, Delta, United and their unions that it will hold informal discussions with the governments of Qatar and the UAE next month.

The $42 billion number has been widely cited. On Tuesday, for example, in a message to United employees, Steve Morrisey, United's regulatory and policy vice president, wrote, ""We have documented evidence that Qatar Airways, Etihad Airways and Emirates Airline have received more than $42 billion in government subsidies."

The new evidence means the number has increased by 16%.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.