British financial services giant Barclays Bank Plc has been imposed a fine amounting £290 million ($452 million) by the UK and the US regulators for manipulating the London interbank offered rates (Libor) and the Euro interbank offered rate (Euribor) during the four-year period starting from 2005.

The Libor and Euribor are benchmark interest rates fundamental to the operation of global financial markets. They directly influence the value of trillions of dollars of financial transactions on a daily basis between banks and other financial institutions as well as public lending.

The matter was under joint investigation by the UK's Financial Services Authority (FSA), the US Commodity Futures Trading Commission (CFTC) and the Department of Justice (DOJ).

Barclay's delinquency relates to the setting of the Libor and Euribor taking into account requests from interest rate derivatives traders, and also influencing the Euribor submissions of other banks involved in the rate setting process.

Barclays was also charged for deliberately reducing its Libor submissions during the global economic crisis for safeguarding the bank's reputation from negative market and media perceptions about its financial condition.

The lender failed to have adequate systems and controls in place for its Libor and Euribor submissions until June 2010.

A major chunk of the fine came from the US regulators CFTC and DOJ which imposed penalties of $200 million and $160 million respectively against Barclay's attempted manipulation and false reporting charges.

Britain's FSA fined Barclays £59.5 million ($92 million), for its misconduct, the largest fine ever imposed by FSA.

FSA's acting director of enforcement and financial crime, Tracey McDermott said in a statement, ''Barclays' misconduct was serious, widespread and extended over a number of years.  The integrity of benchmark reference rates such as Libor and Euribor is of fundamental importance to both UK and international financial markets.  Firms making submissions must not use those submissions as tools to promote their own interests.''

The authority has given a 30-per cent settlement discount to Barclays for fully cooperating with the investigation, without which the fine would have been £85 million.

The FSA is now looking into other banks involved in the wrongdoing.

''The FSA continues to pursue a number of other significant cross-border investigations in this area and the action we have taken against Barclays should leave firms in no doubt about the serious consequences of this type of failure,'' McDermott said.

CFTC's director of enforcement David Meister said in a separate statement: ''The American public and our markets rely upon the integrity of benchmark interest rates like Libor and Euribor because they form the basis for hundreds of trillions of dollars of transactions and affect nearly every corner of the global economy.''

''Banks that contribute information to those benchmarks must do so honestly,'' he said.

Libor is based on rate submission by a select panel of major banks including Barclays, and is calculated and published daily for different currencies by the British Banker's Association (BBA).

Euribor is also computed in a similar way by the European Banking Federation (EBF) that measures the cost of borrowing in the eurozone.

For the relevant period, the Libor panel consisted of 16 banks and the Euribor panel consisted of 40 banks.

Regarding the settlement, Barclay's chief executive Bob Diamond said that the events which gave rise to the resolutions relate to past actions which ''fell well short of the standards'' to which Barclays aspires in the conduct of its business.

To reflect the bank's collective responsibility, Diamond along with three other executives have voluntarily agreed with the board to forgo their annual bonuses this year.