Credit Suisse said internal and external investigations found that Peter Goerke was "placed under observation by a third-party firm on behalf of Credit Suisse for a period of several days in February 2019."

It said that investigators concluded the operation was ordered by Pierre-Olivier Bouee, then the chief operating officer. Credit Suisse announced in early October that Bouee and the head of its global security services had quit over a decision to snoop on a former wealth management chief, Iqbal Khan, who had joined rival Swiss bank UBS.

The bank said that those responsible failed to disclose the earlier observation of Goerke, who was its personnel chief, when they were questioned about the Khan case. It said they also "took care not to leave any identifiable trace in the bank's systems" of the operation.

The external investigation found no indication that CEO Tidjane Thiam or other executives or directors knew anything about the surveillance of Goerke before media reported on it, Credit Suisse said. The bank has already said there is no evidence that Thiam was informed about the observation of Khan.

Chairman Urs Rohner said that the snooping on Goerke was "inexcusable."

"We are aware that the observations of Iqbal Khan and Peter Goerke have damaged the reputation of our bank," he said, adding that the company's board of directors has taken measures to show that it "firmly rejects a culture of observation."

The board has now decided to formally terminate Bouee's contract, Credit Suisse said.