ZURICH (Reuters) - Private detectives from security firm Investigo, hired to shadow a former Credit Suisse CSGN.S manager Iqbal Khan, took defensive action when Khan tried to photograph one of them with his mobile phone, an Investigo memo seen by Reuters said.

FILE PHOTO: Iqbal Khan, former CEO International Wealth Management of Swiss bank Credit Suisse attends the company's annual shareholder meeting in Zurich, Switzerland April 26, 2019. REUTERS/Arnd Wiegmann/File Photo

Credit Suisse hired security firm Investigo to tail former International Wealth Management boss Iqbal Khan, who left the bank in July, to try to ensure he did not poach any colleagues before starting a new job next month at rival UBS UBSG.S, two sources familiar with the matter told Reuters.

Credit Suisse declined to comment on Tuesday.

Khan filed a criminal complaint last week alleging threats and coercion after a confrontation on Sept. 17, during which Swiss media reported that Investigo detectives sought to take Khan’s mobile phone after he tried to take a photo of their car.

A spokesman for Khan declined to comment on the incident. Khan’s spokesman denied that Khan tried to poach Credit Suisse staff for his new employer, calling such suspicions “absurd.”

Prosecutors have opened an investigation into possible threats or coercion. Credit Suisse on Monday said an internal inquiry was under way.

The Investigo memo seen by Reuters on Tuesday, which referred to the alleged confrontation with Khan, said the detectives were taking defensive action.

“Our employee acted as per instructions defensively,” the Investigo memo, seen by Reuters, stated.

An Investigo representative said he could not comment on the memo or any details of the incident prior to the release of other parties’ statements, but said it was very unlikely that one of the firm’s detectives would act in such a way.

“I can’t imagine that any of the employees, as I know them, would pull the phone out of Mr Khan’s hands,” he said. “That would be one of the most ill-advised actions you could take.”

Credit Suisse Chairman Urs Rohner and CEO Tidjane Thiam had earlier pointed to “significant inaccuracies” in media reporting of the incident, which they said in a staff memo “sensationalised” the facts and events.

Three employees of the security firm were detained by authorities over the incident last week, Investigo’s representative said, but were released the same day.