Yes, if the termination has been executed without the prior approval of the concerned authority, you can challenge it.
According to the Section 33 of the Industrial Disputes Act of 1947 -
A prohibition is imposed on the employer from altering or modifying the terms of service of its employee or workmen as per their prejudice or to completely terminate their services during the pendency of any such proceedings, also including the conciliation proceedings, in respect of an industrial dispute.
The underlying principle behind this provision is simple. No employer takes kindly to an employee or workman questioning or acting against an action taken against him by the management, especially by raising an industrial dispute.
If an employee or workman has challenged any disciplinary action taken against him/her, without regard to the facts, it is common for the employer to consider such a workman as a troublemaker who the employer should relieve itself from.
Thus, this section seeks to protect a workman or employee from victimization and unfair treatment by the employer on the grounds of him having raised an industrial dispute against the employer.
It should also be noted that sub-section (1) of the Section states that without any prior approval of the concerned authority before whom such proceedings are pending, no contrary or hostile action, including dismissal or discharge from service, can be undertaken by the employer against the employee or the workman concerned in regard to matter connected with the dispute.
However, it shall also be noted that sub-section (2) of the Section states that throughout the pendency of any such proceeding regarding an industrial dispute, the employer may in harmony with the standing orders valid to the employee or workman concerned in such dispute (or when there are no standing orders, in that case, with accordance to the terms of the contract, between him and the employee or workman) - (a) alter, regarding to any matter not connected with the dispute, the conditions of service applicable to that employee or workman immediately before beginning of such proceeding
(b) or for any wrongdoing or misconduct not linked with the dispute, release or punish, whether by dismissal or any other way, that workman providing no such workman shall be discharged or terminated unless he has been paid wages for a month and an formal submission has been made by the employer before the authority before which the proceeding is pending for sanction of the act of the employer.