Barclays Bank chairman Marcus Agius resigned on Monday over an interest rate rigging affair as the bank faced possible criminal prosecution in a scandal that has sullied London's image as a financial centre.
The beleaguered bank announced Agius' departure and promised an independent audit, amid wider questions about the future of chief executive Bob Diamond and the ethics of London's financial sector, the City.
Britain's Serious Fraud Office (SFO) said it was considering whether it was "appropriate and possible to bring criminal prosecutions" over the issue, adding that it hoped to reach a conclusion within a month.
Prime Minister David Cameron also announced a parliamentary inquiry into the revelations that Barclays traders had lied about the interest rates other banks were charging it for loans.
The scandal, which might implicate other international banks, concerns manipulation of the Libor and Euribor rates which play a key role in global markets, affecting what banks, businesses and individuals pay to borrow money.
Barclays said that Agius, who has chaired the bank for six years, would remain in his post until a successor was found.
"The buck stops with me," Agius said in his resignation statement, less than a week after the bank was fined £290 million ($455 million, 360 million euros) by British and US regulators for attempted rigging.
"I am truly sorry that our customers, clients, employees and shareholders have been let down.
"Last week's events -- evidencing as they do unacceptable standards of behaviour within the bank -- have dealt a devastating blow to Barclays' reputation."
Barclays said it would launch an independent audit that would "undertake a root and branch review of all of the past practices that have been revealed as flawed since the credit crisis started" about five years ago.
The bank insisted that it would establish "a zero tolerance policy for any actions that harm the reputation of the bank."
The SFO said on Monday that it had been working closely with the Financial Services Authority watchdog during the latter's investigation into Libor rate manipulation.
"Now that the investigation into the issue of regulatory misbehaviour has concluded, the SFO are considering whether it is both appropriate and possible to bring criminal prosecutions," the office said.
Cameron, meanwhile, told parliament there would be a full parliamentary inquiry into the scandal which would get to work "immediately".
"This committee will be able to take evidence under oath," he said.
"It will have full access to papers, officials and ministers, including ministers and special advisers from the last government."
Cameron said Britons wanted "to see bankers who acted improperly punished, and they want to know we will learn the broader lessons of what happened in this particular scandal."
The bank's share price nonetheless jumped 3.22 percent on Monday to close at 168.10 pence on the benchmark FTSE 100 index, which was up 1.25 percent.
The gains helped the bank's share price to recover from last week's heavy losses that wiped billions of pounds from Barclays' market value.
"Investors seemed to view the resignation of its chairman as a step in the right direction after the LIBOR scandal broke last week," said David Jones, chief market strategist at IG Index.
But there was continued speculation over whether Diamond, a high-profile and highly paid banker, would keep his job amid widespread calls for him to go.
US national Diamond, who was in charge of Barclays' investment arm at the time of the suspected manipulation, is to face questions from British lawmakers on Wednesday.
Markets were also wondering whether the latest banking scandal would result in a radical shake-up of the way in which business is conducted across the City, amid pressure from high up the political ladder.
"We need to take action right across the board," Cameron said as he announced the parliamentary inquiry into rate-rigging.
"Introducing the toughest and most transparent rules on pay and bonuses of any major financial centre in the world, increasing the taxes banks must pay," he said.
"Ensuring tough civil and criminal penalties for those who break the law. And above all, clearing up the regulatory failure left by the last Labour government."
Barclays is the first major financial institution to settle following investigations on both sides of the Atlantic.
On Sunday it emerged that bailed-out Royal Bank of Scotland (RBS) had sacked four traders over their alleged involvement in the affair, raising suspicions that the practice was widespread.