The Financial Conduct Authority (FCA) said Hayes, a former UBS (>> UBS Group) and Citigroup (>> Citigroup) derivatives trader serving an 11-year sentence for conspiracy to rig global Libor interest rates, was not a "fit and proper person".

But it said the case has been put on ice until after the Criminal Cases Review Commission (CCRC), which investigates where people have lost an appeal but believe they have been wrongly convicted, examines his case.

Hayes, who became the first person jailed worldwide in 2015 for Libor manipulation offences, maintains his innocence and said he welcomed a decision that allowed him to concentrate fully on the CCRC investigation.

"I'm pleased that the FCA has accepted my CCRC application is substantive and expects it to be considered seriously," he said in a statement released by his lawyers.

"There is a huge amount of new evidence available and I will fight my conviction until the truth comes out."

Hayes referred the FCA's planned ban to the Upper Tribunal, which hears appeals on cases brought by the regulator. The FCA said on Wednesday the Tribunal would delay a decision until after a CCRC ruling.

If the conviction is not upheld, the FCA will need to begin fresh proceedings on different facts if it maintains Hayes is not fit and proper, the Tribunal said.

Hayes, a gifted mathematician with mild Asperger's syndrome, was initially sentenced to 14 years in prison in 2015 for conspiracy to rig the London interbank offered rate (Libor), a benchmark for rates on around $450 trillion worth of loans worldwide, while a Tokyo-based trader from 2006 to 2010.

The sentence - one of the longest for white-collar crime in Britain - was reduced to 11 years on appeal. But his attempt to overturn his conviction failed and London's Court of Appeal blocked any further appeal at the Supreme Court.

Britain's CCRC agreed in April to review Hayes's case to see whether it could be referred back to the Court of Appeal.

Hayes and his family have raised more than 90,000 pounds ($118,000) through a crowdfunding campaign to fund the appeal.

(Reporting by Kirstin Ridley; Editing by Rachel Armstrong and Alexander Smith)

By Kirstin Ridley

Stocks treated in this article : Citigroup, UBS Group