The Central Bureau of Investigation (CBI) has started an inquiry against Sterlite Industries Chairman Anil Agarwal to probe alleged irregularities in the disinvestment of Hindustan Zinc Ltd on the basis of "oral information" provided by a complainant, Minister of State for Finance J D Saleem told Lok Sabha on Friday. He said CBI had registered a preliminary inquiry related to the disinvestment of the company between 1997 and 2003, during the NDA government.