Legal action even after resignation...

Dear Sir, Iam keen in knowing whether any company can take legal action on their ex employee?? I would like to narrate my case as under: I was part of one of the reputed company of India, wherein I worked for 3 years. Last month HR dept. Of this company asked me to meet and accordingly during our meeting they gave me termination letter (no justified reason was mentioned in that termination letter). On other hand during that meeting they said that seeing your future it is better that I give my resignation, which I wrote in paper instantly and gave. The very next morning HR called me stating to return that original termination letter and inturn they will give xerox copy of accepted resignation letter. Which I collected very next day. Now today from reliable sources I understand that ex company is planning to take legal action against me. Just to inform you that they are of the opinion that I was actively involved in certain type of financial dealings with vendors. Please note all the rate approvals was done by my reporting boss over mail. According after his approval business with vendors were done. Please advise me what course of action should I take now. Till now I have not received any verbal or written communication from ex company or any advocate on this concern. regards