3. (1) If, on the expiry, whether before or after the commencement of this Ordinance, of the period of any lease in respect of any land or building of which a Port Authority is the lessor, or on the determination of such lease on the ground of breach of any covenant or in pursuance of a condition in the lease imposing any obligation on the lessee to give up possession of the demised land or building in the event of such land or building being required for the purposes of a Port Authority, the lessee refused or failed, or refuses or fails, to vacate and deliver vacant possession of such land or building to the Port Authority, then, notwithstanding anything contained in any other law for the time being in force or in any contract, such Port Authority may, by notice in writing, require such lessee to vacate and deliver vacant possession of such land or building, and to remove structures, if any, erected or built thereon by him, within such time as may be specified in the notice. (2) If the Port Authority is satisfied, after making such enquiry as it may think fit, that a person is an unauthorised occupant of any land or building, it may, by notice in writing, require such person to vacate such land or building, and deliver vacant possession thereof to it, and to remove structures, if any, erected or built thereon by him, within such time as may be specified in the notice. (3) If any person to whom a notice is issued under sub-section (1) or sub-section (2) - (a) fails to comply with the notice, the Port Authority shall make a complaint in writing to that effect to the Authorised Officer; or (b) vacates the land or building, but does not remove the structures thereon, the Port Authority may take possession of such land or building and demolish such structures.