Britain's fraud prosecutor on Tuesday charged former UBS trader Tom Hayes with eight counts of conspiracy to defraud, as part of a global investigation into the manipulation of benchmark interest rates.

Hayes, 33, was arrested by police and the Serious Fraud Office last December as part of an inquiry stretching from the U.S. to Japan. He was charged by U.S. prosecutors last year.

Authorities are pursuing those they allege conspired for years to manipulate Libor, the London interbank offered rate, which is a crucial benchmark affecting trillions of dollars of mortgages and other loans worldwide.

Hayes was 27 when he joined Swiss bank UBS in Tokyo in 2006, becoming a senior and highly-valued trader of interest-rate derivatives indexed to yen-denominated Libor. He generated nearly $260 million in revenues by late 2009, when he left UBS to join Citigroup after a dispute over his salary.

He left Citigroup less than a year later.

In a brief statement, the SFO said Hayes would appear before Westminster Magistrates Court in London at 10 a.m. (0900 GMT) on Thursday, adding that its investigation into Libor rigging continued.