Dear Subramaniyan,
In the absence of a notice clause for unilateral termination of the contract of employment, neither party is required to give notice. If, on the contrary, a notice clause is present prescribing a notice period, it should be the same for both the employer and the employee, including any lieu of condition as an alternative to ensure compliance.
Regarding the issue, by giving advance notice to serve the entire notice period in full or in part before resignation as per the notice conditions stipulated already, the employee makes an implied offer which is accepted by the employer upon acting on the resignation. Any action by the employer such as immediate relieving before the expiry of the notice period, for any reason according to their convenience, will constitute a counter offer. This counter offer requires the acceptance of the same by the employee who is willing to serve the notice period already offered by them. Logically and legally, therefore, the employer is obligated to pay the notice salary in that situation.