Barclays has launched a "root and branch" audit of its banking and business practices as the Libor-fixing scandal, which has cost the British lender £3.6bn in market value, claims the career of chairman Marcus Agius.

Agius, 65, said he was forced to stand aside as chairman after the "devastating blow" the bank's reputation had suffered in the wake of the scandal and the record £290m fine levied by authorities in Britain and the United States.

Agius, who is also chairman of the British Bankers' Association, will stay with Barclays during the search for a replacement, although newly-appointed deputy chairman Michael Rake, 64, is likely to act as point man on the board of directors.

John Sutherland, the former Cadbury Schweppes plc chairman and a current board member of Barclays, will lead the search for Agius' replacement.

At the same time, Rake, a director at Barclays since 2008 and the current chairman of BT Group plc, will oversee an independent audit of Barclays' business practices, which will publish a report upon completion.

Both Agius and Barclays chief executive officer Bob Diamond, 60, are due to appear before lawmakers on the Treasury Select Committee to answer questions regarding the growing controversy surrounding not only the Libor-fixing allegations, but also banking ethics and culture in general. Prime Minister David Cameron's coalition government has called for an inquiry into the future of Libor, a key benchmark lending rate across 10 different currencies that forms the pricing foundation for hundreds of trillions of dollars worth of securities worldwide.

Barclays shares have fallen 17 percent since the FSA announced its record fine of $59.5m on 27 June, wiping away more than £3.6bn in shareholder value. Diamond and three of his most senior colleagues, chief operating officer Jerry del Missier, corporate and investment banking head Rich Ricci and finance director Chris Lucas, have all waived their bonuses for this year as a result of the fine and accompanying explosive allegations.

Both the UK's Serious Fraud Office and the US Department of Justice are either actively investigating the allegations of bid-rigging or considering launching a formal probe into the matter.

Barclays