Tom Hayes' legal team are locked in a spat with the Serious Fraud Office over the return of the convicted Libor rigger's passport, as the UK prosecution agency continues to hold onto it nine years after it was first relinquished to authorities.

The former UBS and Citigroup trader was required to hand his passport to the SFO in 2012 as part of the terms of his arrest for possible involvement in a market-wide conspiracy to manipulate the London Interbank Offered Rate, a benchmark that helps determine interest rates on mortgages and sizable corporate loans.