Where the Minister in pursuance of the authority conferred on him by this section has ordered any person to leave New Zealand, any Magistrate, on the ex parte application of the Minister and on such evidence as the Magistrate thinks fit, whether or not such evidence would be admissible in a Court of Law, may direct, if he thinks such a course is necessary in the public interest and whether default has been made in obedience to the order or not, that the person shall be detained in such custody as the Magistrate shall order until that person can be placed on a ship or aircraft which is leaving New Zealand.

Where a Magistrate gives a direction under subsection (6) of this section he shall issue a warrant for the arrest and detention of the person to whom the direction relates and that person may thereupon be arrested by any constable, detained in custody as required by the direction, placed on board a ship or aircraft which is about to leave New Zealand, and detained there until the ship or aircraft has left New Zealand:

“Provided that every such warrant shall expire on the twenty-eighth day after the day on which the person to whom it relates was arrested or taken into custody pursuant to it.”