NEW YORK (CBSDFW.COM/AP) — Qatar Airways is attempting to buy a 10 percent stake in Fort Worth-based American Airlines, triggering U.S. antitrust oversight over deals of such size.

American said in a regulatory filing Thursday that the bid was unsolicited, but that there have been conversations between the CEOs of both airlines.

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Qatar submitted a filing under the Hart-Scott-Rodino Act, which is subject to review by the Justice Department’s Antitrust Division.

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Qatar plans to buy at least $808 million in common stock. American’s certificate of incorporation restricts anyone from buying 4.75 percent or more of its shares without advanced board approval following a written request. American says it hasn’t received such a request.

Qatar is one of three Persian Gulf carriers that some U.S. carriers have criticized for unfair competition. Officials with American, Delta, and United Airlines say the tens of billions of dollars the United Arab Emirates (UAE) gives to their state-owned airlines undermines the “Open Skies” agreements that U.S. and international airlines operate under.

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(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)