Under Indian law, is it allowable for a department (or department head) to bypass the a formal open "request for tender" process, by instead calling limited tender among arbitrary selected venders. Specifically, does this (or is this likely to) violate vigilance rules of central vigilance commission or state vigilance commission, for a state-owned company for generating thermal power?

The company has a official public notice published in its website stating that material and services will be procured through e-tender and directing interested bidders to buy Digital Signature Certificates for participating in the e-tendering process. 

However, in one of this company's power plants, procurement is not handled through the open e-tendering process, but instead tender is only available to vendors arbitrarily selected by an official.

**Is the "limited tendering" policy described above legal? If not, is it a form of corruption? Could this be evidence of a kickback scheme or other systematic corruption?**