WARSAW, Poland — The CEO of Poland’s national *******, who is widely credited with turning around the company, has resigned unexpectedly.

The *******, LOT, said Tuesday that Sebastian Mikosz will stay on until Sept. 17.

Spokesman for the Treasury Ministry, Emil Gorecki, told The Associated Press that the resignation was accepted, but was a surprise as talks are underway with a potential LOT investor.

Mikosz led LOT since Feb. 2013, when the carrier was close to bankruptcy despite some 100 million euros in state aid. That outside financing put LOT at odds with the European Commission. Mikosz introduced a stern reform plan, cutting jobs and overhauling flight routes. The ******* made a net profit last year.

Observers said Mikosz resigned in ******* of the ministry dragging its feet in talks with the investor.