Citigroup declined comment on Monday on a guilty verdict against former trader Tom Hayes, who worked for the U.S. bank for 10 months, in the first trial of a defendant accused of Libor interest rate rigging.

"Tom Hayes was terminated in September 2010 following an incident that was reported to compliance. Citi also reported the matter to the appropriate regulators at the time," Citigroup said in an emailed statement.

The bank declined further comment after a jury in London delivered its verdict and found Hayes, 35, guilty of charges of conspiracy to defraud.