Thank you very much Shri Subbaraoji for updating me with the latest developments.
My reply to the post is regarding the legal issue of engagement of contract labour during a strike of regular employees. I have quoted the provisions in the Industrial Disputes Act 1947. It is upto that member whether to follow or not.
The issue raised by you regarding contract employment which is coming under "Contract Labour (Regulation and Abolition) Act 1970. Legally, there are regulations (and not ban) in India in engaging employees on contract basis to ensure non-exploitation, safety and welfare.
Those who have grievances can get it redressed through collective bargaining, various grievance redressal system and legal forums. If any authority empowered to enforce fails, it also can be questioned, using RTI Act onwards.
I appreciate your words.