Sydney police are continuing to identify people involved in a riot after Monday's church stabbing.

The 16-year-old suspect remains in hospital under police guard for the alleged terrorist attack.

A 19-year-old has been placed under house arrest over his alleged role in the riot.

New South Wales Police Commissioner Karen Webb says they're arresting people as they're identified.

She says they believe there could be up to 50 people to identify, maybe more.

Webb says 51 officers were injured in the riot, and are recovering.