Subject to the provisions of this part, no person shall interfere with an aircraft which has been involved in an accident, the wreck or wreckage, a part or component thereof or anything transported therein or any marks resulting from the accident which may be of assistance in an investigation-
(a) until authorised to do so by the investigator-in-charge; and
(b) until, in the case of an aircraft which must be cleared by a customs officer by virtue of the provisions of the Customs and Excise Act, 1964 (Act No. 91 of 1964), clearance has been issued or permission granted by such officer.