Apologies and regrets from HSBC's bosses in the British Parliament today.

MPs have questioned CEO Stuart Gulliver and chairman Douglas Flint over the revelations that its Swiss operation helped wealthy clients dodge tax.

They're facing a seemingly endless list of inquiries and questions have been raised by the Treasury Select Committee over their personal tax affairs and lavish bonuses.

Stuart Gulliver put on the record an apology for the unacceptable events that took place in the mid-2000s.

"It clearly was unacceptable we very much regret this and it has damaged HSBC's reputation."