Bank of America, Citigroup and Barclays have received subpoenas from U.S. regulators probing the setting of the London interbank offered rate, or Libor, for U.S. dollars between 2006 and 2008, the Financial Times said, citing people familiar with the investigation.

On Wednesday, Swiss bank UBS said it had received subpoenas from U.S. and Japanese regulators regarding whether it made improper attempts to manipulate LIBOR rates, the benchmark price for interbank borrowing costs.

The Financial Times said the regulators are narrowing the probe to a handful of banks among the 16 that help the British Bankers' Association (BBA) set LIBOR rates.

The banks could not immediately be reached by Reuters for comment outside regular U.S. business hours.

(Reporting by Sakthi Prasad in Bangalore; Editing by Vinu Pilakkott)