IRCON, a Railways PSU, had engaged consultants for execution of two overseas rail projects and accordingly, it paid about Rs 422 crore over the last seven years between 2007 and 2014.
However, an audit objection was raised over the appointment and payment to consultants, and the matter was brought before the Railway Minister last week.
Taking the audit objection seriously, Prabhu has sought a detailed investigation in the case and directed the authorities concerned to initiate action accordingly, official sources said.
Railways has already introduced e-tendering and e-procurement system to bring about probity and transparency in the system.
The idea is to make the entire procurement and tendering system available online and do away with manual process, the sources added.