You have served your organization for 3 years.
Even you want to leave the org now, request to HRD for an offer letter, appointment letter, relieving & experience letter. Aforesaid letters will substantiate your experience, which would benefit you to negotiate & put your candidature ship for better opportunity.
I would suggest not to go into legal action etc...Instead be polite & get you work (Letters) done.
I do appreciate your opinion, but what if i already have a an offer after at long time, which exactly matches my career aspiration, but with the prerequisite that i need to join them within a week's time..or else the offer shall stand revoked. I understand that my current employer will not want me to leave the organisation, that too with such a short notice. In that case, what do you suggest?
Take the them into confidene (Company given you offer). Make things crystal clear to them, that this is the issue you are facing with present employer. If they give you time to settle down issues with current employer, well & good.
Remember to indulge into dual employment is crime (If any such condition mentioned in appointment letter).
1:- If you have not signed any terms & conditions with current employer, then you can leave the company without any exit formalities. But you will lose your experience letter.
2:- If you go for legal action without having an appointment letter against the company, you will stand no where. (Don't even think about it).
3:- Why all these years you didn't asked for appointment letter?
4:- Try to have constructive dialogue with the management & sort out things.
You have a choice to make : risk losing your new job or risk alienating your existing company for ever.
The choice must be made by comparing your short and long term goals. What happens if your future employer where you go after the next job does a background verification ? They will surely get a negative feedback. But on the other hand, if you leave this one, will you get the same opportunity soon ?
Irrespective of whether you got an appointment letter, you have been working for 3 years and are deemed to know and to agree to the rules of the organisation. This includes notice pay. So either you need to serve notice period or pay for the same. It's as simple as that.