LONDON (AFP, BLOOMBERG) - A trader who worked for UBS and Citigroup on Monday became the first person to be convicted in Britain of rigging the Libor inter-bank lending rate.

Tom Hayes, 35, was found guilty following a trial at London's Southwark Crown Court.

Hayes, the first person to stand trial for manipulating Libor, was found guilty of eight counts of conspiracy to rig the benchmark rate.

After a week of deliberations, jurors found that he conspired with traders brokers to dishonestly game the London interbank offered rate to benefit his own trading positions. Each count carries a maximum term of 10 years in prison.

Prosecutors said during the nine-week trial that Hayes was the "ringmaster" of a global network of 25 traders and brokers from at least 10 firms who tried to manipulate Libor on an industrial scale. He would bribe, bully, cajole and reward his contacts for their help in skewing the benchmark, used to price more than US$350 trillion (S$480 trillion) of financial contracts from mortgages to credit cards and student loans.

The scruffy, blond-haired Hayes has been the public face of the global scandal over Libor rigging since he was first charged by U.S. officials in 2012. Authorities have levied US$9 billion in fines against banks and brokerages, including a US$1.5 billion penalty for UBS.

Citigroup has been censured by Japanese regulators over its involvement.

Central to the case against Hayes were 82 hours of interviews with the U.K. Serious Fraud Office in 2013, during which he detailed his methods and even named co-conspirators. One of the traders he fingered was his own step-brother, Peter O'Leary, then a graduate trainee at HSBC Holdings Plc in London.

In the SFO interviews, Hayes coolly explained how the scam started soon after he joined UBS as a yen interest-rate swap trader in Tokyo in the summer of 2006 and continued through to his firing by Citigroup in September 2010.