"I can confirm that we have launched an investigation of Mr. Kopper on suspicion that he violated insider trading regulations," the spokeswoman said. She added that the investigation has been handed over to prosecutors in Frankfurt.

She was confirming a corresponding report in the regional daily Stuttgarter Zeitung.

The newspaper said the probe would try to establish whether Kopper told Deutsche Bank chief Josef Ackermann of the resignation of DaimlerChrysler chief executive Jürgen Schrempp before the move was officially made public.

The paper said the probe was based on investigations by the financial sector watchdog BaFin surrounding the resignation of Schrempp last summer, which led to a sharp rise in DaimlerChrysler's share price.

Deutsche Bank sold shares

Deutsche Bank used the share rally to reduce its stake in the carmaker from 10.4 to 6.9 percent. It sold 35 million shares for more than 1.3 billion euros ($1.56 billion) for a pretax profit of 300 million euros.

Kopper, formerly head of Deutsche Bank, has headed DaimlerChrysler's supervisory board since 1998.

Both DaimlerChrysler and Deutsche Bank have so far declined to comment on the probe.