The Central Government may, by notification, exempt from the application of this Act, or any provision thereof, and for such period as it may specify in such notification-

(a) any class of enterprises if such exemption is necessary in the interest of security of the State or public interest;

(b) any practice or agreement arising out of and in accordance with any obligation assumed by India under any treaty, agreement or convention with any other country or countries;

(c) any enterprise which performs a sovereign function on behalf of the Central Government or a State Government: