U.S. investigators probing the alleged manipulation of interbank lending rates are now focusing on possible violations of a commodities law that has previously been used to send financial executives to prison, the Financial Times said, citing people familiar with the probe.

U.S. authorities are modeling their Libor probe on an earlier prosecution of three energy companies for violations of the Commodity Exchange Act, which resulted in criminal settlements and prison terms of up to 14 years, the paper said.

As per the act, it is illegal to transmit a false report that would affect the price of a commodity.

The interbank lending probe, led by the U.S. Commodity Futures Trading Commission (CFTC) and the Department of Justice (DOJ), is examining possible collusion between traders and bank treasury departments in 2007 and 2008, the paper said.

The commission is examining whether traders placed bets on future yen and dollar rates and colluded with bank treasury departments, who help set the Libor index, to move the rates in their direction, FT said.

The CFTC and DOJ 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)