Reserve Bank of India (RBI) Deputy Governor Swaminathan J criticised some non-banking financial companies (NBFCs) for lax loan appraisal practices and charging excessive interest rates, even as he acknowledged the sector's rapid expansion over the past decade, especially in recent years. "Unfortunately, some NBFCs seem to believe they can operate with weak underwriting in the pursuit of fast growth while levying excessive and unsustainable interest rates - sometimes disguised as upfront or processing fees - followed by aggressive recovery methods in case of default," Swaminathan said at the conference of NBFCs in Chennai last month.