(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.