Barclays Boss,Bob Diamond says the bank's senior managers acted as soon as they were aware of the practice
The boss of Barclays has insisted he will not resign after staff rigged the key lending rate between banks, reports the BBC.
Bob Diamond was speaking at a meeting of analysts at US bank, Morgan Stanley.
And in a letter agreeing to give evidence to MPs, Diamond condemned the inappropriate behaviour of a "small number" of employees who had tried to make profits for their own benefit.
On Thursday, the prime minister said the bank's management faced "serious questions" after it was fined £290m.
Some MPs - including Tories Steve Baker and Nick De Bois - have suggested Diamond should resign and former Liberal Democrat leader Paddy Ashdown told BBC One's Question Time his position was now "untenable".
Meanwhile, Barclays and other banks face the threat of criminal investigation in the UK over the scandal.
Royal Bank of Scotland has said that it expects to reach a settlement in a few months. One report said the bank faced a fine of £150m for market manipulation but RBS said it did not recognise that figure.
In his open letter to Andrew Tyrie MP, the chairman of the Commons Treasury Committee, Diamond pointed out that authorities found no evidence that knowledge of the manipulation, for which it has been fined £290m, went any higher than "immediate desk supervisors".
But he admitted that the bank's control systems should have been much stronger.
He added: "When the trader conduct was first discovered by more senior management, steps were immediately taken to stop it, and it was reported to the authorities."
Diamond's comments come after Prime Minister David Cameron said: "The whole management team [at Barclays] have got some serious questions to answer. Let them answer those questions first.
"Who was responsible? Who was going to take responsibility? How are they being held accountable?"
Labour leader Ed Miliband said those Barclays staff found to have committed the wrongdoing "should face the full force of the law".
Diamond also said that Barclays was now "completing a review of employee conduct for all those involved", and that "all appropriate options will be pursued for those who have a case to answer, ranging from the clawback or withholding of remuneration to being asked to leave the bank".