One of Britain's top banking regulators said the process of setting the London interbank offered rate or Libor was under review.
"It is clear that urgent reform of the Libor compilation process is required," said Martin Wheatley, managing director of the Financial Services Authority.
"Such reform may include amendments to the technical definitions used for Libor, the associated governance framework and the role of official regulation," Wheatley said.
The New York Times reported that an official review of the Libor by the FSA began Monday.
The Libor, which is the average interest rate banks pay each other for short-term loans, as reported to the British Bankers Association, has been the subject of intense scrutiny and regulators the subjects of harsh criticism since it was announced in June that British bank Barclays would pay a $450 million settlement to end charges that it tried to manipulate the Libor.
Bank e-mails openly discussed various bank officers manipulating the bank's figures. With a low rate, a bank appears healthier to investors and regulators, an incentive for banks to send in a low number.
But the Libor is an important benchmark rate used to set the rate on an estimated $3.5 trillion in consumer and personal loans.
The FSA said their review would be made public by October.
After the controversy broke, the European Commission said it would outlaw Libor manipulation.
U.S. regulators were also involved in the Barclays settlement. Last week, U.S. Treasury Secretary Timothy Geithner was questioned by members of the House Committee on Financial Services on his response to finding out about Libor manipulation as far back as 2008.
"We took the initiative to bring ... concerns to the broader regulatory community. I believe we did the necessary and appropriate thing very early in the process," Geithner said.