An Act to facilitate compliance by Australia with obligations under the Rome Statute of the International Criminal Court, and for related purposes
Part 2—General provisions relating to requests by the ICC for cooperation
9 Urgent requests for cooperation and requests for provisional arrest
A request for cooperation made in urgent cases, and any request for provisional arrest, may be made by using any medium capable of delivering a written record.
If a request is made or sent in the first instance in a manner specified in subsection (1), it must be followed as soon as practicable by a formal request made in accordance with section 8.
Provisional arrest
Request for provisional arrest
EDIT.