Regulators are to fine Barclays chief executive Jes Staley for trying to discover the identity of an anonymous whistleblower.
The Financial Conduct Authority (FCA) and Prudential Regulation Authority (PRA) are taking enforcement action following a year-long investigation.
In a joint statement the FCA and PRA said they had issued confidential draft warning notices with their reasons for the proposed enforcement actions.
The regulators allege Staley's actions represented a breach of Individual Conduct Rule 2, which require people to act with due skill, care and diligence. Each regulator has proposed that he pay a financial penalty.
A statement said: 'The FCA and PRA are not alleging that he [Staley] acted with a lack of integrity or that he lacks fitness and propriety to continue to perform his role as group chief executive officer.'
Staley has a period during which he may review the decision.
Barclays said it would decide what adjustments should be made to Staley's pay once the case has concluded, but backed the chief executive to continue in his role.
'The Barclays board continues to have unanimous confidence in Mr Staley and continues to recommend his re-election as a director at the Barclays annual general meeting on 1 May 2018,' it said.
Regulators launched their probe into Staley last April. The fact Staley had tried to identify the author of the letter first came to the attention of the Barclays board in early 2017, as a result of a concern raised by an employee regarding, among other matters, the adequacy of Barclays' whistleblowing procedures.
The board immediately instructed an external law firm, Simmons & Simmons, to conduct a investigation into the matter, led by Sir Gerry Grimstone, deputy chair and senior independent director, on behalf of the board.
The board also promptly notified the FCA and PRA and other relevant authorities.
The investigation by Simmons & Simmons concluded Staley acted honestly, but mistakenly, believed that it was permissible to identify the author of the letter.
'I have apologised 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.
After concluding its probe, the PRA and FCA decided to stop short of taking enforcement action against Barclays, but have proposed the bank provide reports on certain aspects of its whistleblowing programme.
In May 2017, Barclays commissioned its own independent reviews of its processes and controls, which resulted in certain enhancements being subsequently made.
The bank also continues to provide information to, and cooperate with, authorities in the US with respect to this matter.