Secretary to the Ministry of the Minister in charge of the subject of Defence or, in a prosecution for an offence under paragraph (b) of subsection (1), a Certificate under the hand of the Secretary to the Ministry of the Minister in charge of the subject of Finance, stating respectively, that the situation envisaged in subsection (1) did in fact exist in relation to national security or public order, or the national economy, as the case may be, shall be admissible in evidence and shall be prima facie evidence of the facts stated therein.