Credit Suisse has confirmed it will investigate reports an outgoing star banker was followed by a trio of its own detectives, with an expert saying the incident could have damaged the firm’s brand as an employer.

Iqbal Khan, the former head of Credit Suisse’s international wealth management business, who is due to start work at rival UBS on 1 October, reportedly became involved in an altercation last week with three men who followed him while he was out in Zurich with his family.

The three men, reportedly dete...