Video report by Tom Bradby
The former Chief Executive of Barclays Bob Diamond said he felt "physically ill" when he read emails between traders involved in rate rigging.
He said the behaviour of those involved was "reprehensible".
Mr Diamond appeared before the Treasury Select Committee to explain how much he knew about rate rigging going on at the bank.
He started by saying "I love Barclays" and he said that a "small group of traitors" were responsible for "reprehensible acts". He also said that Barclays has received disproportionate attention because it was the first bank to be explicitly linked to rate rigging.
He batted away questions about the trigger for his resignation and whether there had been any pressure on him to leave from regulators such as the Bank of England or FSA.
He said he did not know whether either regulator spoke to Barclays chairman Marcus Agius in the run up to his departure.
Mr Diamond has been asked several times about the memo detailing a phone conversation between in which the bank's deputy governor Paul Tucker appears to imply that the bank should lower its Libor rate.
The memo includes the lines:
He said that he did not interpret Mr Tucker's comments as an instruction to lower the bank's Libor rates.
He said he was concerned at the time that there was a perception in the Government that Barclays couldn't fund itself and might need to be nationalised.
Asked who he thought the "figures within Whitehall" mentioned in the memo could be, he said:
"I would only be speculating if I told you who."
Mr Diamond resigned as Barclays' chief executive yesterday in response to revelations that staff at the bank were fixing the Libor rate, which determines the level at which financial institutions lend to each other.
Roberts Garnier MP, a member of the Treasury Select Committee, said that the aim of today's interview was to discover what Mr Diamond knew, when he knew it and what he did to remedy the situation. He added that he would welcome the opportunity to hear from Paul Tucker in the coming days.
Mr Tucker has asked the Treasury Select Committee to arrange a hearing to allow him to "clarify the position" of the Bank of England. A date has not been set yet.
Three senior executives at Barclays have resigned over the Libor rate-rigging revelations: Bob Diamond, Chief Operating Office Jerry del Missier and Mr Agius. Mr Agius has returned to the bank on a temporary basis to help select Mr Diamond's successor.
Although Barclays has ordered an internal investigation into its practices, the bank has been largely defensive. Speaking to ITV News, Mr Agius said that Mr Diamond's decision to resign was "personal":
Mr Diamond's resignation statement did not include any admission of guilt: