Tom Hayes, a former UBS Group AG and Citigroup Inc. trader convicted in 2015 for rigging LIBOR, called for an "urgent" public inquiry after a recording of a 2008 telephone call suggested that the Bank of England was involved in manipulating the key financial benchmark, The (U.K.) Daily Telegraph reported April 10.

The recording has seemed to reignite the controversy about the role authorities played in setting LIBOR during the financial crisis.

Hayes reportedly said that the central bank's involvement in lowballing LIBOR "was a key plank of my defense."

Meanwhile, Hayes and former Barclays Plc trader Jonathan Mathew are considering fresh appeals amid questions about the credibility of an expert prosecution witness at another rigging trial, Bloomberg News reported April 7. Hayes' sentence was reduced to 11 years from 14 years and Mathew was sentenced to four years in prison, the report noted.

During the retrial of former Barclays traders Ryan Reich and Stylianos Contogoulas, expert witness Saul Haydon Rowe said he needed help understanding some of the practices he testified about, Bloomberg reported. Reich and Contogoulas, who were accused by the U.K. Serious Fraud Office of making false submissions for U.S. dollar LIBOR between 2005 and 2007, were recently acquitted.

Rowe, a former trader who works for Turing Experts Ltd., admitted that he texted other traders for help on some terms while on the witness stand. He has testified for the SFO at four LIBOR-rigging trials, including Hayes', Bloomberg added.

Hayes reportedly said April 6 that he will add disclosures about Rowe to his case-review application, adding that the SFO knew about "the limits of [Rowe's] expertise."