(1) The Minister may, at any time, by notice in writing served on the holder of a permit, vary, suspend or revoke the permit where he is satisfied that ¾

(a) a provision of this Act relating to the permit or a condition imposed in respect of the permit has been contravened; or

(b) it is necessary or expedient to do so in order properly to regulate the activities with which this Act is concerned.

(2) A suspension of a permit may be of indefinite duration or for a period specified in the notice.

(3) Where proceedings for an offence in relation to a permit are commenced during a period of suspension of the permit, the suspension may be continued until the proceedings (including any appeal) are completed.

(4) During the period of suspension of a permit, the permit has no force or effect, but the period of currency of the permit continues to run.

(5) The suspension of a permit does not prevent its revocation.

(6) The revocation or suspension of a permit takes effect when notice of the revocation or suspension, as the case may be, is served on the holder of the permit or on such later date (if any) as is specified in the notice.