Marcus Agius, the man at the top of Barclays when its traders manipulated a global benchmark interest rate, appeared before a hostile panel of lawmakers as part of an investigation into a row that has caused widespread public anger and which threatens to draw in a dozen other global banks.

Agius was the first Barclays executive to quit when the scandal erupted last week, but that was not enough to protect Diamond, who was forced out a day later. Agius has had to stay on to find a successor to Diamond.

"Bob Diamond has voluntarily decided to forgo any deferred consideration and deferred bonuses to which he otherwise would have been entitled," Agius, 65, said.

"The maximum amount would be £20-million."

Diamond, 60, would, however, receive a year's pay and a cash payment instead of a pension, together worth £2-million, Agius said.

Barclays confirmed the payoff arrangement in a statement that quoted Diamond as saying he hoped his decision would help the bank move on.

"The wrongful actions of a relative few should not detract from the outstanding work that Barclays employees carry out each day on behalf of clients and customers around the world," he said.

British Prime Minister David Cameron welcomed Diamond's decision to forgo his bonus.

Barclays has been fined more than $450-million for its part in manipulating the London Interbank Offered Rate, the interest rate that underpins transactions worth hundreds of trillions of dollars.