Former Barclays chief executive Bob Diamond, who resigned over a rate-rigging scandal, is not claiming bonuses worth £20m sterling, the bank's chairman said today.

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

British Prime Minister David Cameron said the decision was a sign Barclays understands public concern that banking culture must change.

Asked by the Treasury Select Committee about the value of the payoff Diamond has waived, Agius said: "The maximum amount would be £20m."

In a separate statement, Barclays said Diamond would still receive up to 12 months' salary, pension allowance and other benefits.

Diamond was one of the world's highest paid bankers, earning a package worth £17.7m last year. He and Agius both resigned last week over revelations that Barclays traders attempted to manipulate key inter-bank lending rates, but Agius is staying on to lead the search for Diamond's replacement.

Barclays was fined £290m last month by British and US regulators for the attempted rigging of the Libor inter-bank lending rate and Euribor, its euro zone equivalent.

The Barclays statement said Diamond had "voluntarily offered to waive all of his unvested deferred bonus awards and long term incentive share awards.

"This is in addition to his previous decision to forgo any consideration for an annual bonus this year," it added.

The bank added that Diamond has also agreed to forgo his contractual entitlement to tax equalisation. "Despite having no personal culpability, he recognises more than anyone the negative attention that they have generated and has taken characteristically strong action to address that," Agius said of Diamond in the statement.

"It is my hope that my decision to step down and today's agreement on my remuneration will help close this chapter and allow Barclays to move forward and prosper," Diamond had said.

The scandal has claimed the job of Barclays' chief operating officer Jerry del Missier as well as those of Diamond and Agius, and threatens to engulf other banks.