HSBC published a full-page letter in British newspapers on Sunday to offer its "sincerest apologies" for past practices at its Swiss private bank, which has been accused of helping clients to evade tax.
Europe's biggest bank admitted failings in compliance and controls in its Swiss operation after media reports that said it had helped wealthy customers to conceal millions of dollars of assets up to 2007.
Britain's Treasury Committee has called the bank's chairman and chief executive to give evidence on the matter on Feb. 25, according to a memo seen by Reuters on Friday.
The bank's letter published in a number of newspapers on Sunday was signed by Chief Executive Stuart Gulliver and said that the reports had been a "painful experience" for its customers, shareholders and employees.
"We must show we understand that the societies we serve expect more from us," Gulliver wrote. "We therefore offer our sincerest apologies."
The bank said that the vast majority of the 140 people named in reports as customers of its Swiss bank had left and that it has since established much tighter controls on who it accepts as customers.
"We have absolutely no appetite to do business with clients who are evading their taxes or who fail to meet our financial crime compliance standards," he said.
The fallout from the claims caused the bank's former boss Stephen Green to step down at financial services lobby group TheCityUK on Saturday.