(1)  A person who –

(a) intentionally delays or obstructs an inspector or a police officer in the exercise or proposed exercise of his powers under section 90 , 90A , 90B , or 90E ; or

(b) without reasonable excuse, fails to produce, or conceals, any substance, plant, or document, or any stocks of a substance or plant, that he is required under section 90 to produce –

is guilty of an offence and is liable on summary conviction to a fine not exceeding 50 penalty units.

(2)  If the admission of an inspector or a police officer to any premises which he seeks to enter in accordance with section 90 or 90E is refused, or is delayed or obstructed for such time that it may reasonably be inferred that the delay or obstruction was intentional, the occupier of the premises, and any other person who refuses, delays, or obstructs the admission of the inspector or police officer, are each guilty of an offence and are liable on summary conviction to a fine not exceeding 50 penalty units.

(3)  In proceedings in respect of an offence against this section in relation to the delaying or obstructing of a police officer or an inspector, if it is shown that the entrance of a police officer or of an inspector into any premises or place was prevented or delayed by the existence of any barrier or obstruction in or on the premises or place, it shall be presumed, unless the contrary is proved, that the barrier or obstruction was intended to prevent or delay the entry into the premises or place of the police officer or inspector.