LONDON (REUTERS) - Tom Hayes, a former UBS and Citigroup trader serving an 11-year jail sentence for conspiring to rig Libor global interest rates, was on Tuesday blocked from appealing to the UK's Supreme Court against his conviction.

Hayes, the first person tried by jury after a global inquiry into allegations of Libor-rigging, has redoubled efforts to overturn his conviction since six former brokers he is alleged to have plotted with were found not guilty in a separate London trial.

London's Court of Appeal on Tuesday formally refused leave for the case to be taken to the UK's highest court, according to a spokesman at the Serious Fraud Office (SFO) prosecutor.

Criminal cases can be referred to the Supreme Court in exceptional case of general public importance.

Hayes, 36, lost his initial appeal against his conviction in the Court of Appeal in December, though that court cut his original 14-year prison sentence - one of the longest on record for UK white collar crime - by three years.

Hayes said in a statement from Lowdham Grange prison in central England that he was disappointed with the decision, continued to maintain his innocence and would pursue all avenues available to him to clear his name.

"My application is clearly in relation to a point of law and is of public importance because it concerns the test of dishonesty that applies to all criminal cases in this country,"he said.