Commercial banks and urban co-operative banks (UCB) will be allowed to rope in at least two auditors not related to each other and will have to take prior approval of the Reserve Bank of India (RBI) for appointment or reappointment of statutory auditors on an annual basis, the central bank said on Tuesday. “For entities with an asset size of Rs 15,000 crore and above as at the end of previous year, the statutory audit should be conducted under joint audit of a minimum of two audit firms,” the RBI said. Any bank with a balance sheet of less than Rs 15,000 crore can have one statutory auditor. However, in all cases, concurrent auditors cannot be appointed as statutory auditors.