First of all the provision of the POA, which states as follows, fully absolves you of any responsibility on behalf of your employer company:
"We hereby agree to ratify all acts, deeds and things lawfully done by our said attorney purusant to this POA and all acts, deeds and things done by our aforesaid attorney shall and shall always be deemed to have been done by us".
So, if you have been made party, that is wrong. Moreover, if the company is a Limited company as governed by the Companies Act, the company, itself is an artificial person in the eyes of law and only Directors of the company are liable for any legal action, not any employee. Contention of the Directors is quite wrong, if they say, "only their attorney should be held responsible and directors of the company should be left out from the inquiry." THEY CANNOT EVADE FROM THEIR LIABILITY & RESPONSIBILITY.
Secondly, if any irregularity has been committed by any employees of the PSU in award of a contract, the PSU should have taken action against its own employees, not the contractors. However, if violation of some statutory provisions have been made or fraudulent activity has been noticed on account of the act of the POA holder of the ABC company, as it seems be there from your supplementary information, the POA holder can also be booked for criminal conspiracy in the process. However, the Directors of the ABC company would be the main accused, not the employee/POA holder.
So, first of all you will have to defend yourself or to become a witness for approval to save yourself and only after you are exonerated of the offence, you can claim damages from your employer company separately.