Former Barclays boss Bob Diamond has admitted there had "clearly been mistakes" and "reprehensible behaviour" at the bank as he was grilled by MPs on the rate-rigging scandal.

Mr Diamond, who resigned as chief executive on Tuesday, was giving evidence to the Treasury Select Committee on the culture he presided over at the bank as staff fiddled the key Libor rate that affects the price of mortgages and loans.

Mr Diamond opened the session by declaring his "love" for Barclays and added: "At the core of the issues there clearly were mistakes, clearly there was behaviour that was reprehensible."

Ahead of the appearance, the American banker disclosed a record of a phone call with Bank of England deputy governor Paul Tucker that ultimately led to staff pushing down the Libor.

Mr Tucker has requested his own appearance before the committee to clarify his role.

Mr Diamond said he did not know whether Barclays chairman Marcus Agius had come under pressure from regulators to bring about his resignation. He suggested that over the weekend he had been determined to stay at the helm of the bank.

But he added: "It was clear to me on Monday that the support wasn't as strong and I needed to take this step."

Mr Diamond suggested he and Barclays had been the victims of an "unfortunate series of events", and there had been problems at other banks.

"I think there has been an unfortunate series of events in the last week around Barclays being identified as the first in what was a report that clearly showed very, very bad behaviour by groups of people."

He insisted that senior executives had dealt with the problems "appropriately" and regulators had praised their co-operation with the investigation.