(4)The provisions of sub-section (2) of section 3 shall apply, for the purpose of proving a purpose prejudicial to the safety of the State, to any prosecution for an offence under this section relating to the naval, military or air force affairs of Government, or to any secret official code in like manner as they apply, for the purpose of proving a purpose prejudicial to the safety or interests of the State, to prosecutions for offences punishable under that section.
