HSBC chief executive Stuart Gulliver has admitted it "sometimes failed to live up to the standards" expected by society in a memo to staff over "painful" allegations of tax avoidance at the banking giant's Swiss subsidiary.
It marks the first apparent expression of contrition from Mr Gulliver in the wake of the affair this week.
Details of the memo emerged as Bank of England deputy governor Sir Jon Cunliffe disclosed that the Bank's Prudential Regulation Authority (PRA) could look into the allegations.
Mr Gulliver wrote in the memo: "I know the recent media coverage about past practices at our Swiss private bank and the financial affairs of some of our Swiss private bank clients has been painful for you to read and watch.
"You have been working tirelessly and with great dedication to build a stronger HSBC with fully global businesses and functions, rigorous controls and the highest global standards, all underpinned by a clear strategy to serve our millions of loyal customers.
"I share your frustration that the media focus on historical events makes it harder for people to see the efforts we have made to put things right.
"But we must acknowledge we sometimes failed to live up to the standards the societies we serve rightly expected from us."