The Swiss investment bank said Monday that ex-chief operating officer Pierre-Olivier Bouée ordered a spying operation on Credit Suisse's former head of human resources for several days in February, and later covered up the scheme.

said that Bouée tapped a "third-party firm" to observe Peter Goerke "on behalf of Credit Suisse." The company did not explain why Bouée had Goerke watched.

Goerke left his HR role and the bank's executive board in late February to become Credit Suisse's senior adviser for new projects in Asia and China.

It's the second time Bouée has been implicated in a spying scandal at the bank. He stepped down this fall after an investigation found that he asked the bank's head of security to spy on Iqbal Khan, Credit Suisse's head of wealth management, in August after crosstown rivalannounced that Khan would be joining them. The head of global security also resigned.

On Monday, Credit Suisse said that Bouée was asked after that incident whether he had ordered surveillance on anyone else. Bouée "did not respond truthfully when asked about any additional observations and did not disclose the observation of Peter Goerke," the bank said in its statement. It added that the board of directors has now decided to fire Bouée. He had earlier resigned.

The board also said it has apologized to Goerke.

The bank enlisted Swiss law firm Homburger to investigate the surveillance of Goerke after media reported that he was a target. A Swiss newspaper, the Neue Zürcher Zeitung said last week that Goerke had been placed under observation. It cited documents and photos.

Credit Suisse said that it found no indication that CEO Tidjane Thiam and other members of the executive board or board of directors knew anything about the latest spying case until the media reported on it. And it said the bank has already put in place "more rigorous internal policies" to stop this from happening again.

"The observation of Peter Goerke, which has now been confirmed, is inexcusable," said Urs Rohner, chairman of the board of directors, in a statement Monday. He said the board "firmly rejects a culture of observation."