(1) The measure levied under rule 12 shall be only for such period of time as may be necessary to prevent or remedy serious injury and to facilitate adjustment.

(2) Notwithstanding anything contained in sub-rule (1) of this rule measure levied under rule 12 shall, unless revoked earlier, cease to have effect on the expiry of four years from the date of its imposition :

Provided that if the Central Government is of the opinion that the domestic industry has taken measures to adjust to such injury or threat thereof and it is necessary that the safeguard measure should continue to be imposed, it may extend the period of such imposition :

Provided further that in no case the safeguard measure shall continue to be imposed beyond a period of ten years from the date on which such measure was first imposed.