Britain's Serious Fraud Office has charged a former trader with conspiracy to defraud in the rigging of a benchmark interest rate.

The UK's fraud office says Tom Hayes, a former trader at UBS and Citigroup, was charged Tuesday as part of the investigation into the manipulation of the London interbank offered rate, or LIBOR.

City of London police charged the 33-year-old with eight counts of conspiracy to defraud. He will appear before Westminster Magistrates' Court at a later date.

U.S. and British regulators have fined two big British banks and Switzerland's largest hundreds of millions of dollars for manipulating LIBOR. The rate provides the basis for trillions of dollars (pounds) in contracts around the world, including mortgages, bonds and consumer loans.