Non-Compete Clause Validity In India

Hi, I have been working for almost 2.5 years in a Service based company which is among the top 5 Indian service companies.
My query is that now i have been offered a job from the client company which i am working for & this offer is almost double the salary than present one, I have accepted the offer also, but now my company got to know about this and trying to initiate legal proceedings against me(location India).
Can any one guide me what are the issues involved in this matter will they hold my relieving letter. the appointment letter states that after separation form the company we are not suppose to take the offer from client or customer for a period of six months with whom we have worked. Please guide me on this issue asap.

The company can hold your relieving letter because it is issued following their internal administrative procedures but they cannot legally block you from joining their competitors because any negative covenant is void. As per section 27 of Contract Act service agreement extending beyond termination of employment is illegal and void.
Please follow my blog article on this also.
Regards,
Madhu.T.K