FRANKFURT (Reuters) - Deutsche Boerse (>> Deutsche Boerse) Chief Executive Carsten Kengeter has not yet been exonerated of insider trading allegations, officials said on Thursday, prolonging uncertainty over his future at the German exchange operator.

A public statement from Deutsche Boerse on Tuesday spoke of a deal from the Frankfurt prosecutor in which Kengeter would be cleared of personal wrongdoing and Deutsche Boerse would be fined 10.5 million euros ($12 million).

However, a spokesman for the public prosecutor in Frankfurt said on Thursday the investigation was "open", and a spokesman for Deutsche Boerse said the proceedings were "ongoing".

German markets watchdog BaFin is now investigating whether Deutsche Boerse's statement misled the public.

In a third probe, a German regional regulator announced on Wednesday that it is assessing the fitness of Deutsche Boerse management amid the insider trading allegations.

The local exchange regulator in Germany's western state of Hesse did not specify who its review focused on. It has the power to remove a board member it deems unfit.

Earlier this year, as Deutsche Boerse discussed a merger with the London Stock Exchange (>> London Stock Exchange), police and prosecutors searched Kengeter's office and home amid concerns over Deutsche Boerse share purchases made months before the announcement of merger talks.

Kengeter has always denied allegations of wrongdoing, saying the purchases were part of an official Deutsche Boerse compensation plan. "Insider trading goes against everything I stand for," he told shareholders in May.

The hypothetical fines of 10.5 million euros on Deutsche Boerse would be for failing to notify the public promptly about the merger talks with the LSE and over the design of its executive share-buying scheme that allowed Kengeter to buy shares in the first place.

Kengeter's three-year contract as CEO expires at the end of March 2018. He has expressed a desire to stay on. The board has been standing behind Kengeter but has balked about an extension until his name is cleared.

Kengeter has kept a low profile since Brussels failed to approve his merger plans with the LSE and amid the insider trading allegations.

The exchange operator has scaled back its ambitious strategy, saying that major mergers were off the table and focusing instead on partnerships, small acquisitions and investment.

Meanwhile, Deutsche Boerse has been trying to cultivate local ties to burnish its image. It plans to spruce up the Frankfurt stock exchange and has sponsored Frankfurt's local soccer team, Eintracht.

(Reporting by Hans Seidenstuecker, Alexander Huebner and Tom Sims; Editing by Edward Taylor and Adrian Croft)

Stocks treated in this article : Deutsche Boerse, London Stock Exchange