Rudiger Grube, the chief executive officer (CEO) of Deutsche Bahn, has unexpectedly stepped down from his post amid a dispute with the railway company's board over his pay.

Gruebe, who has been the CEO of the German state-owned railway firm since May 2009, is said to have offered his resignation during a board meeting on Monday (30 January). According to an unnamed company source, Gruebe made the move after the board offered him only a two-year renewal of his contract as against the three-year extension and pay rise he was seeking.

According to the German firm's last annual report, Grube was being paid a fixed annual salary of €900,000 (£769,414, $962,876) along with €522,000 in short-term bonuses.

Meanwhile, the German firm did not give any specific reasons for Grube's exit. In a statement, it said that its board had unanimously approved Grube's "request for his appointment to CEO to be rescinded effective immediately and for an agreement to be concluded to terminate his current contract." The company further thanked Grube for his commitment to the firm over his nearly eight years as its CEO.

Utz-Hellmuth Felcht, chairman of the Supervisory Board also thanked Grube for his contribution to the company. "Dr. Rüdiger Grube has made a lasting contribution to DB, in particular through his work to make the company fit for the future. He has left his mark on Deutsche Bahn as a driver of both digitalization and the Zukunft Bahn quality program," he said.

With regards to his replacement, the Germany railway company, which owns Arriva in the UK, said it would make a prompt decision on his successor. It added that amid applicable rules, its CFO Richard Lutz will serve as interim CEO till a replacement is appointed.

Per-Ola Hellgren, analyst at Landesbank Baden-Württemberg, a German-based commercial bank, said the move was unexpected. "It's a big surprise...If [Deutsche Bahn] had shares traded, they would have dropped now," the analyst was quoted as saying by the Financial Times.