Employer refusing to provide release letter - Is their any way?

My notice period is 60 days in my current organisation but i am giving them 31 days notice. They are not willing to clear my dues or release. I have already giving proper handover and knowledge transfer. Is their any way by which i can get release letter.
P.s- Buyout option is not there. Currently I am on my notice period.

Visit your nearest Labour Office if not applicable then consult a good lawyer.

Firstly when you have accepted the 60 day notice period you should have stuck by it or else you need to convince the Management for getting all dues including relieving letter.
That is the best option. If those do not work out then take a call for approaching other legal options, as they all are costly and time consuming.

Either you have to convince the management on your early release or need to wait for the full notice period to be over. You cannot claim that you are right to be released in one month time as you had accepted the term of two month notice at the time of joining. It is not something that has been added by the management subsequently and/or without mutual agreement. Always better to avoid confrontation and see if your new employer can wait for the extended period. Moreover if you can convince the new management, it would add value to yourself as being honest and trustworthy than fighting it out without much chance in this instance.

you can request your manager to waive off the rest notice period days or else you have to pay the amount for the pending notice period days. So that the smooth relieving process will be followed.