At any time after the filing of the indictment or information, any party may move for a pretrial conference to consider matters relating to classified information that may arise in connection with the prosecution. Following such motion, or on its own motion, the court shall promptly hold a pretrial conference to establish the timing of requests for discovery, the provision of notice required by section 5 of this Act, and the initiation of the procedure established by section 6 of this Act. In addition, at the pretrial conference the court may consider any matters which relate to classified information or which may promote a fair and expeditious trial. No admission made by the defendant or by any attorney for the defendant at such a conference may be used against the defendant unless the admission is in writing and is signed by the defendant and by the attorney for the defendant.