3. (1) This Act shall apply to every employment under the Government, and, subject to the provisions of sub-section (2), to any employment or class of employment which the Government may, by notification in the official Gazette, declare to be an employment or class of employment to which this Act applies. (2) No declaration under sub-section (1) shall be made in respect of any employment or class of employment unless the Government is of opinion that such employment or class of employment is essential,-(a) for securing the defence or the security of Bangladesh or any part thereof, or ¹[(b) for the maintenance of such supplies or services which are essential to the life of the community.] (3) A declaration under sub-section (1) shall remain in force for a period of six months which the Government may, by notification in the official Gazette, extend for further periods not exceeding six months at any time.