Barclays’ head of security is facing an internal investigation over his role in trying to uncover a whistleblower, according to reports.

On Monday the bank announced that financial regulators are investigating Barclays boss Jes Staley, after he tried to identify a whistleblower who sent two letters to the board and a senior executive in June 2016, raising concerns about the conduct of a senior employee, reported to be Tim Main.

According to the BBC, Mr Staley had asked security head Troels Oerting to identify the author of those letters and the broadcaster on Wednesday reported that Mr Oerting was now also being investigated.

Mr Main was a former colleague of Mr Staley’s for several years at JPMorgan, who the Barclays boss then hired.

Mr Oerting’s LinkedIn account shows he joined Barclays from Europol where he was head of the law enforcement agency’s cybercrime unit and is also a member of Interpol’s Global Cybercrime Expert Group.

Barclays declined to comment on any internal investigations relating to Mr Oerting.

Barclays said on Monday that Mr Staley had taken measures to identify the author of the letters because he considered them to be “an unfair personal attack on the senior employee”.

The bank said that Mr Staley was subsequently informed that it was not appropriate to do so.

By law, whistleblowers are protected and are not allowed to be treated unfairly or lose their job for reporting wrongdoing. Mr Staley in a statement on Monday said that he had not been aware of the fact that it was not permissible to identify the author of the letters.