Evidence of an official instrument issued by the Governor - General of New Zealand, or by or under the authority of a New Zealand Minister, may be adduced by producing:
(a) if the instrument was made by the Governor - General in Council of New Zealand -- a copy of, or an extract from, the instrument purporting to have been certified as a true copy or extract by the Clerk of the Executive Council of New Zealand; or
(b) otherwise-- a copy of, or an extract from, the instrument purporting to have been certified as a true copy or extract by a New Zealand Minister.