Regulators on both sides of the Atlantic failed to act on clear warnings that the Libor interest rate was being falsely reported by banks during the financial crisis, it emerged last night. A cache of documents released yesterday by the New York Federal Reserve showed that US officials had evidence from April 2008 that Barclays was knowingly posting false reports about the rate at which it could borrow in order to assuage market concerns about its solvency. An unnamed Barclays employee told a New York Fed analyst, Fabiola Ravazzolo, on 11 April 2008: So we know that we're not posting, um, an honest Libor." He said Barclays started under-reporting Libor because graphs showing the relatively high rates at which the bank had to borrow attracted "unwanted attention" and the "share price went down". The verbatim note of the call released by the Fed represents the starkest evidence yet that Libor-fiddling was discussed in high regulatory circles years before Barclays' recent 290m fine. The New York Fed said that, immediately after the call, Ms Ravazzolo informed her superiors of the information, who then passed on her concerns to Tim Geithner, who was head of the New York Fed at the time. Mr Geithner investigated and drew up a six-point proposal for ensuring the integrity of Libor which he presented to the British Bankers Association, which is responsible for producing the Libor rate daily. Mr Geithner, who is now US Treasury Secretary, also forwarded the six-point plan to the Governor of the Bank of England, Sir Mervyn King.