Hi
1) Supreme court has issued many orders in the past wherein it has NOT permitted regularisation/absorption of contract employees in government jobs without any set procedures and processes.
2) The judgments of Supreme Court in Surinder Prasad Tiwari v. U.P. Rajya Krishi Utpadan Mandi Parishad, National Fertilizers Ltd. v. Somvir Singh, State of Karnataka v. Umadevi have always held that "appointment in the State and its instrumentalities should only be in accordance with the rules and procedure relating to regular recruitment".
3) In your case since the PSU has by itself by its arbitrary and discriminatory action opened up a pandora's box where in it has regularised the services of some contract staff (foreign staff) in the year 2013, it is crystal clear that the PSU has acted against the judgment of supreme court in Umadevi's case.
4) You are at liberty to file a case under Article 226 in Delhi HIgh court and pray the court to declare the act of PSU selectively regularising the foreign based contract workers as arbitrary, discriminatory and illegal.
5) The outcome of you filing the case in High court might result in either of the following:
a) The PSU may choose to contest the claim in High court (which is highly unlikely)
OR
b) Avoid unnecessary litigation and fire from Delhi High court, might absorb you in regular employment. however this outcome is dependent on PSU management OR on the collective voice of contract workers(india based) who choose to challenge the PSU in court.
Hope this information is useful.