(a)  discovery and inspection;

(b)  enforcing the attendance of any person, including any officer of a banking company and examining him on oath;

(c)  compelling the production of books of account and other documents; and

(d)  issuing commissions.

(1A) If the Principal Director General or Director General or Principal Director or Director or Joint Director or Assistant Director or Deputy Director, or the authorised officer referred to in sub-section (1) of section 132 before he takes action under clauses (i) to (v) of that sub-section, has reason to suspect that any income has been concealed, or is likely to be concealed, by any person or class of persons, within his jurisdiction, then, for the purposes of making any enquiry or investigation relating thereto, it shall be competent for him to exercise the powers conferred under sub-section (1) on the income-tax authorities referred to in that sub-section, notwithstanding that no proceedings with respect to such person or class of persons are pending before him or any other income-tax authority.

(2) For the purpose of making an inquiry or investigation in respect of any person or class of persons in relation to an agreement referred to in section 90 or section 90A, it shall be competent for any income-tax authority not below the rank of Assistant Commissioner of Income-tax, as may be notified by the Board in this behalf, to exercise the powers conferred under sub-section (1) on the income-tax authorities referred to in that sub-section, notwithstanding that no proceedings with respect to such person or class of persons are pending before it or any other income-tax authority.

(3) Subject to any rules made in this behalf, any authority referred to in sub-section (1) or sub-section (1A) or sub-section (2) may impound and retain in its custody for such period as it thinks fit any books of account or other documents produced before it in any proceeding under this Act :

Provided that an Assessing Officer or an Assistant Director or Deputy Director shall not—

(a)  impound any books of account or other documents without recording his reasons for so doing, or

(b)  retain in his custody any such books or documents for a period exceeding fifteen days (exclusive of holidays) without obtaining the approval of the Principal Chief Commissioner or Chief Commissioner or Principal Director General or Director General or Principal Commissioner or Commissioner or Principal Director or Director therefor, as the case may be.