If from information received or otherwise, a police officer has reason to suspect the commission of an offence which he is empowered to investigate under section 17 and considers that for the purpose of investigation or inquiry into such offence, it is necessary to inspect any bankers books, then, notwithstanding anything contained in any law for the time being in force, he may inspect any bankers books in so far as they relate to the accounts of the persons suspected to have committed that offence or of any other person suspected to be holding money on behalf of such person, and take or cause to be taken certified copies of the relevant entries therefrom, and the bank concerned shall be bound to assist the police officer in the exercise of his powers under this section:
Provided that no power under this section in relation to the accounts of any person shall be exercised by a police officer below the rank of a Superintendent of Police, unless he is specially authorised in this behalf by a police officer of or above the rank of a Superintendent of Police.
Explanation.--In this section, the expressions "bank" and "bankers' books" shall have the meanings respectively assigned to them in the Bankers' Books Evidence Act, 1891 (18 of 1891).