The Reserve Bank of India said on Thursday that non banking financial companies (NBFCs) with asset size of more than Rs 50,000 crore should appoint a chief risk officer in a move to tighten regulation after a series of defaults at top lender Infrastructure Leasing & Financial Services' (IL&FS).

The government took control of IL&FS last year after its default triggered fears about contagion in India's financial sector.

An independently functioning chief risk officer with clearly specified role and responsibilities has to be appointed by NBFCs, the Reserve Bank of India said in a statement.

"With the increasing role of NBFCs in direct credit intermediation, there is a need for NBFCs to augment risk management practices," the central bank said in a statement.

The central bank said that the chief risk officer has to be appointed for a fixed tenure and cannot be removed without board approval.