Hong Kong/London (CNN Business) Credit Suisse CEO Tidjane Thiam has resigned after acknowledging that two spying scandals last year had "disturbed" the Swiss bank.

Credit Suisse CS The board of directors unanimously accepted Thiam's resignation at a meeting on Thursday, appointingveteran Thomas Gottstein as the new CEO, the Swiss investment bank said in a statement Friday.

Bouée Last year, Credit Suisse's ex-chief operating officer, Pierre-Olivier Bouée, was implicated in two separate spying operations, one involving the former head of wealth management Iqbal Khan . Khan had defected to crosstown rival UBS andBouée reportedly feared that he might try to poach Credit Suisse employees and clients. The bank said he had ordered the surveillance to protect its interests.

Bouée stepped down after that operation came to light. More recently, he was blamed for ordering a spying operation on Credit Suisse's former head of human resources for several days last February. CNN Business has attempted to contact Bouée for comment.

"I had no knowledge of the observation of two former colleagues. It undoubtedly disturbed Credit Suisse and caused anxiety and hurt. I regret that this happened and it should never have taken place," Thiam said in the statement.

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