The day after Thomas Hayes was dismissed by Citigroup for rigging Libor, the derivatives trader fired off an email accusing his boss of manipulating similar benchmarks.

Mr Hayes, who is on trial in London, said Brian McCappin, head of Citigroup’s investment bank in Japan, asked traders to fiddle with the Tokyo interbank offered rate, according to an email shown to jurors yesterday.

“Brian McCappin would talk to the cash desk in Tokyo and ask them to move Tibors,” Mr Hayes wrote to a counterpart at Barclays in a September 2010 message. “I never spoke to the Tokyo cash desk as they were a different business area.”

Hayes (35) is accused of eight counts of conspiracy to manipulate the Libor interbank rate. The former trader, who worked at banks including UBS, has pleaded not guilty.

– (Bloomberg)