U.S and British regulators are investigating whether banks understated Libor to reduce borrowing costs and downplay investor panic during the financial crisis.
The regulators are investigating whether Barclays' traders and its treasury operations improperly communicated, violating "Chinese wall" rules to prevent sharing information between the bank's different units, the Financial Times reported on Thursday.
Barclays' treasury unit helps set the Libor rate.
The investigators are also looking into whether there was "any improper influence" on the information that Barclays submitted daily as part of a survey that is used to set the inter bank borrowing rate, the newspaper reported.
A Barclays spokesman declined to comment on the newspaper's report on Thursday.
UBS disclosed earlier this month that it was a target of the probe. Bank of America Corp and Citigroup Inc have also received subpoenas from U.S. regulators, the Financial Times has reported.
U.S. regulators have also asked JPMorgan Chase & Co, Deutsche Bank, Citigroup and Bank of America to make employees available as witnesses in the probe, Bloomberg News reported on Wednesday.
About $350 trillion worth of financial products globally reference Libor, and lower levels for the rate could have robbed lenders and investors of significant amounts of interest income. Borrowers, on the other hand, would have benefited.