Current Organisation Not Giving Relieving Letter

Hi,
i had been working in a company for the past 4 years. I had given resignation letter and they ask me to serve 3 months notice period. I agreed upon on serving 3 months notice period and conveyed to the new employer (they also agreed after 3 months)
But current organisation ask me to complete the project then only they relieve and threating me.
But i am not in situation to continue after 3 months notice period
I need clarification,
1. Whether i am legally to stay after 3 months notice period.
2. what are the other options to approach
Kindly advice me still 2 week left to end 3 months notice

The solution is as follows
Case 1: Generally, in these cases, the HR Manager of the prospective employer would generally ask for the resignation letter you have submitted, the communication you had with your current employer and their willingness to relieve you after 3 months.
By providing this information, the prospective employer mostly accepts you into their organization. Open up the communication and see the results
Case 2: Explain the current employer that you would help them in completing the project by working on weekends and ask for the relieving letter
Take the above 2 chances. Hope for the best.

Hi,
Let me inform
three month notice period is your company policy this mentioned in your appointment order ?
Based on this only we can decide the time of notice period.
Regards
Prabakar

Hi,
What Prabakar asks is right.....! first check your appt letter and if mentioned for 3 mths their is no other option. And if not than you can speak to your HR and inform them that you you will try to finish you work within three month[ TRY TO FINISH] ....!
Or you can speak to you new company HR about this prob I think they will understand it if logical explation is given.
All the best just be in co ordination with you company and new company will get a solution for your problem dont worry................!
Congrates for new job...........!

Thanks to all,
In my current organisation it is 3 month or 3 month pay notice period as per policy.
Since project is on going is important they threating me you should be min of 3 months. I have completed my current on going work and some dependable work in progress. But it seems to be late and it may extend after 3 months.
New employer agree to come after 3 months with specific date. But current organisation no idea in relieving.
Hope i am not in position after 3 months serving.
How to tackle further...?

Hi mdu,
I understand ur situation, please be calm and take a rational decision, dont feel emotional by putting words like employers threatening you. There will be someone to understand you in your concern just go and speak to them especially in the hr department, keep progressing try to get your relieving order from the hr department at the end of 2.5 months just follow up. No one can threaten you , please dont be afraid they cannot do anything. Everything is in ur hands just enjoy your days and be positive and rational. If there is any mistake in this article please excuse me.
Regards,
ajithaa

Yes they had written.But my point is that its already passed 3 months then why they ask for 3 months salary?