The Reserve Bank on Wednesday flayed lenders for keeping interest rates high and flagged concerns over base rate and marginal cost of fund-based lending rate (MClR), saying these have not improved monetary transmission. An internal RBI group also suggested switching over to an external benchmark in a time-bound manner so that better rates are available to borrowers. “The RBI study group has observed that internal benchmarks such as the base rate/MClR have not delivered effective transmission of the monetary policy,” RBI said in a report today. The group was constituted by RBI to study various aspects of the MClR system from the perspective of improving the policy transmission.