The Bank of England has confirmed that it received US recommendations to overhaul the Libor interest rate.
The bank said it had passed them on to the banking group responsible for the rate.
Documents obtained by news agency Reuters showed that US Treasury Secretary Timothy Geithner pressed the British central bank in June 2008 to make changes to the way that the widely used interest rate benchmark was set.
Geithner, who was the head of the New York Federal Reserve Bank at the time, sent a private email to BoE Governor Mervyn King.
The email recommended six ways of enhancing the credibility of the London interbank offered rate.
The BoE passed on Geithner's thoughts in an email to the British Bankers Association (BBA) which at that stage had already decided to launch a review of the rate.
"Both the Bank and the Federal Reserve were assured by the BBA that it would take on board the recommendations, either through actions or through questions on which it would consult," the BoE said in a news release.
More than a dozen banks are under investigation by authorities in Europe, Japan and the United States over suspected rigging of Libor, which is used in financial contracts worth hundreds of trillions of dollars globally.
The June 1, 2008 email, first reported by the Washington Post, included a two-page memo dated May 27 of that year that suggested establishing best practices for calculating Libor, "including procedures designed to prevent accidental or deliberate misreporting."
It recommended the British Bankers' Association require that auditors for banks reporting their borrowing costs for the calculation of Libor attest to the accuracy of their rates.
The New York Fed is due to release documents later today that it has said will show it took "prompt action" four years ago to highlight problems with Libor.
The Bank of England also published a number of emails between members of its staff, and the BBA.
"Changes are being made to incorporate the views of the Fed. There is no show stopper as far as we can see," Angela Knight, the BBA's former head, said in a June 3 email to Paul Tucker, who was then the BoE's executive director for markets.
He is currently deputy governor and a candidate to replace King at the top.
London-based Barclays is the only bank so far to admit any wrongdoing in giving false information as part of the complex process of setting Libor, in order to influence the pricing of derivatives and also to rebut speculation about the weakness of its balance sheet during the financial crisis.
Britain's third biggest bank was dropped from a Japanese bond deal this week. Meanwhile, the council in the central English city of Leicester said it was pulling out £6m in deposits.
"We share in the anger expressed by many customers by the recent scandal," said Rory Palmer, deputy mayor of Leicester, in a statement. "We will not be investing in Barclays in the foreseeable future."
