FRANKFURT (Reuters) - German prosecutors on Friday said they had opened an investigation of Kai Diekmann, publisher of best-selling European tabloid newspaper Bild, days after parent company Axel Springer announced he had resigned.

Kai Diekmann, Chief Editor of Bild, Germany's newspaper speaks during an exclusive interview in his office at the Springer - publishing house in Hamburg, January 16, 2007. REUTERS/REUTERS/Morris Mac Matzen

Diekmann has long been one of the most powerful media figures in Germany, with his newspaper becoming known for either making or breaking careers of political leaders and celebrities.

“We have a criminal investigation against Kai Diekmann,” a spokesman for the prosecutor’s office in Potsdam, Germany said.

The spokesman declined to give any further details about the reasons for the investigation involving Diekmann, who became Bild’s publisher after serving as editor in chief from 2001 until the end of 2015.

German weekly Der Spiegel reported on Friday that a Springer employee had filed a sexual harassment complaint against Diekmann in Potsdam last year. Reuters was unable to determine how the matter was resolved or if it related to the criminal investigation.

Diekmann declined to comment on both the investigation and the allegation in the magazine when contacted by Reuters.

His lawyer, Otmar Kury, said the accusations were unfounded. “We have full confidence in the work of the investigating authorities,” Kury said.

Axel Springer said that it had held its own internal investigation after an employee came forward with sexual harassment allegations and, following a “very intensive and in-depth” investigation, had not found evidence of any criminal behavior.

However, the company had alerted the public prosecuters and passed on its findings, a company spokeswoman said.

The company declined to give further details about its internal investigation.

Springer said last week that Diekmann would leave the company -- at his own request -- on Jan. 31 this year after more than 30 years with the company. .

The company did not give a reason for his departure.