British lawmakers will question the chief executive and chairman of HSBC, Europe's biggest bank by market value, amid allegations it helped the wealthy dodge taxes.

CEO Stuart Gulliver and Chairman Douglas Flint are appearing Wednesday before the House of Commons Treasury Committee.

The testimony comes days after Gulliver became personally mired in the scandal involving the group's private Swiss bank. Gulliver acknowledged a Guardian newspaper report that he had an account at the same unit.

Gulliver says he opened the account through a Panamanian company to protect his own privacy, preventing other HSBC colleagues to see what he was earning. The Panamanian account has been closed as his pay is now disclosed to shareholders.

Also facing questions from the committee is HM Revenue and Customs chief executive Lin Homer.