Sachin - the answer is no. An employer may not extend notice period unless there is a provision written in appointment letter. If 60 days is the notice period, then an employer should not hold the employee beyond 60 days for any unspecified causes.
In certain circumstances, we see that employers do resort to unprofessional practices like this - it is not right. An employer and employee relationship is governed by an employment contract, simply.
If this has occurred with you, you have the legal right to obtain in writing specifying the causes of extension of your notice period.
Employers do have a backgrounds like unsatisfactory work performance, insubordination, indiscipline, etc. to hold back an employee from going. Please ensure that you are are fulfilling your duties timely and in a right manner.
Thank you.