Barclays Plc was fined 290 million pounds ($453.2 million), the largest penalties ever imposed by regulators in the U.S. and U.K., after admitting it submitted false London and euro interbank offered rates.

Chief Executive Officer Robert Diamond and three lieutenants will forgo their bonuses as a result, Britain's second-biggest bank by assets said in a statement today. Derivatives traders requested the false submissions in the Libor and Euribor setting process, as they were "motivated by profit and sought to benefit Barclays' trading positions," Britain's Financial Services Authority said.

The settlements with the FSA, the U.S. Commodities Futures Trading Commission and U.S. Department of Justice are the first in an international investigation into whether banks tried to manipulate Libor, the benchmark rate for $360 trillion of securities, to hide their true cost of borrowing. Citigroup Inc., Royal Bank of Scotland Group Plc, UBS AG, ICAP Plc, Lloyds Banking Group Plc and Deutsche Bank AG are among firms that are being probed by regulators worldwide into how Libor is set.