The Financial Conduct Authority (FCA) and the Prudential Conduct Authority (PRA) have opened an investigation into both Staley and Barclays's actions when pursuing the author of a letter believed to have originated from a whistleblower.

"I have apologized to the Barclays Board, and accepted its conclusion that my personal actions in this matter were errors on my part. I will also accept whatever sanction it deems appropriate," Staley said in a statement on Monday morning.

"Our whistleblowing process is one of the most important means by which we protect our culture and values at Barclays and I certainly want to ensure that all colleagues, and others who may utilize it, understand the criticality which I attach to it," he added.

The Barclays Board found Staley had "honestly, but mistakenly" sought the identity of the letter's author without appropriate governance. The whistleblower was not identified by the Barclays boss and the board has now accepted his apology.