The Bank of England has said it will step up its scrutiny of big banks’ efforts to phase out the Libor benchmark, after being “surprised” to find “very different levels of readiness” among companies for its formal end in 2021.

The central bank released a review of the City’s progress toward phasing out Libor on June 5, praising “much good work that is already underway” but warning that many banks are still insufficiently prepared for the transition.