Bob Diamond, the Chief Executive Officer of Barclays Plc has stepped down from his top job at the bank following an interest rate-rigging scandal that affects several other leading banks around the world.

Barclays has been slapped with a fine of half a billion dollars due to its role in the changing the global benchmark interest rate.

"The external pressure placed on Barclays has reached a level that risks damaging the franchise - I cannot let that happen," Diamond said in a statement. His resignation comes into effect immediately. Chairman Marcus Agius now has the responsibility to find a new CEO for the banking firm.

Diamond had written a strong letter to staff members indicating he will continue. However, he decided to quit after Prime Minister David Cameron and finance minister George Osborne announced an inquiry into the scandal.

Diamond had appeared before the parliamentary inquiry into the manipulation of interbank lending rates that underpins as much as $360 trillion of loans and financial contracts. Investigators have found that Barclays traders rigged the Libor interest rate from 2005 to 2009 at a time when Diamond headed the British bank's investment banking operations.