(b)such officer, authority or body performing functions under any other law, if in the opinion of the Central Government it is necessary so to do in the public interest, as it may specify by notification in this behalf,any such information received or obtained by any income-tax authority in the performance of its functions under this Act, as may, in the opinion of the Board or other income-tax authority, be necessary for the purpose of enabling the officer, authority or body, to perform his or its functions under that law.