Who is authorised to undertake the audit of a registered person?

The Commissioner of CGST/Commissioner of SGST or any officer authorised by him, by way of a general or a specific order, may undertake audit of any registered person for such period, at such frequency and in such manner as may be prescribed.

(ICAI FAQ PUBLICATIONS : -06-09-2017 AUDIT BY TAX AUTHORITIES : FAQ NO. 1)