Dismissed Thai Airways president Piyasvasti Amranand has filed a lawsuit against the carrier for the "unfair termination of his contract".
Amranand filed the suit with the Thai labour court this morning, a day after his last as the carrier's president, says a Thai spokeswoman.
She could not provide details regarding the lawsuit.
Media reports in Thailand meanwhile quote Amranand saying he is suing Thai's board of directors for his unfair dismissal. He wants the carrier to either reinstate him as the airline president or compensate him up to the original expiry of his contract in July 2013, they add.
Amranand's contact was terminated after a board meeting on 21 May because of "communication issues".
The former government minister told Flightglobal last week that he wants the board to give a "credible reason" for his dismissal, calling allegations of his communication "ludicrous".
A disagreement over aircraft procurement appears to be at the heart of the surprise dismissal. Amranand believes the carrier needs 38 new-generation aircraft as part of its long-term fleet plans, but the board preferred to postpone the acquisition to avoid affecting the carrier's financial status.
Amranand was appointed president in 2009 and succeeded in returing the carrier to profitability.
He had also publicly criticised the government on several occasions, notably its refusal to give the green light to form Thai Tiger. One source says his comments on the issue made him unpopular with many in the government.