BARCLAYS chairman Marcus Agius quit on Monday, saying an interest rate rigging scandal had dealt "a devastating blow" to the bank's reputation and "the buck stops with me".
Mr Agius, chairman at Barclays for five-and-a-half years, will stay in his position until a succession plan is assured.
Pressure has built on him and CEO Bob Diamond to quit following a $453m fine for Barclays by British and US regulators last week for making inaccurate submissions on the Libor interest rate.
"Last week's events - evidencing as they do unacceptable standards of behaviour within the bank - have dealt a devastating blow to Barclays reputation ... the buck stops with me and I must acknowledge responsibility by standing aside," Mr Agius said in a statement.
Both Mr Diamond and Mr Agius have been called to appear this week before British legislators on the Treasury select committee in the wake of the fine. The inquiry will focus on possible criminal sanctions against people who breach future regulations on the rate, said a Treasury spokesman, who declined to be named.
Prime Minister David Cameron last week called for accountability to go "all the way to the top".
"The review into the regulation of Libor will also look at criminal sanctions that should be in place," Treasury Minister Mark Hoban said.
The news that Barclays traders tried to fix Libor rates rocked the City of London financial district. It also wiped billions off Barclays' market value in a week when British banks were separately sanctioned for mis-selling interest rate insurance. Barclays shares fell as much as 18% on Friday, and are down 32% this year.
Banks may face billions of dollars in costs from litigation.
The two scandals have fuelled public distrust of an industry resented for its role in the 2008 financial crisis and for big bonuses for top executives - prompting ministers to signal a regulatory crackdown.
The Libor debacle centres on traders submitting false information on Barclays' borrowing rates to make the bank look more secure or, in some cases, to turn a profit.
British regulator the Financial Services Authority lacks the power to impose criminal prosecutions for manipulating Libor but has said it is in talks with Britain's Serious Fraud Office over the case.
British Justice Secretary Ken Clarke on Saturday called for criminal prosecutions of bankers and urged stronger rules despite opposition from the financial sector.