Lenders should brace for increased scrutiny of their efforts to replace the scandal-plagued London interbank offered rate, or Libor, as the deadline for phasing out the nearly 50-year old rate-setting benchmark approaches, a global watchdog warned on Wednesday.

Chief executives of several major Australian, British and European banks have been sent letters from top banking regulators requesting updates on their efforts to adopt alternative risk-free benchmarks, said the Financial Stability Board in its annual report on the reform effort.