Riot police are moving to restore order at the Christmas Island detention centre following unrest sparked by the death of an asylum seeker.
Australian Immigration Minister Peter Dutton confirmed reinforcements had arrived.
"There's an operation under way," he told reporters in Canberra today.
"The government's not going to cower in the face of the activities of some of these criminals."
Centre operators had control of the administration block and health clinic as of last night night and authorities had been patrolling the perimeter of the facility.
Mr Dutton said police had settled some compounds today.
"The officers were met with little resistance," he said.
The minister was confident authorities would contain the situation and warned those who had damaged Commonwealth property would face the full force of the law.
Refugee advocate Ian Rintoul said about 50 people slept on a sports oval overnight and were fearful riot police would use excessive force.
Police were making announcements over loud speakers demanding detainees return to their rooms and discard weapons.
"They have drones circulating above the centre," Mr Rintoul said.
The unrest was sparked after a small group of Iranian detainees staged a protest at the death of an escapee on Sunday.
However, convicted criminals whose visas have been cancelled and are at risk of deportation have also been involved in the disturbance.
There are about 40 Kiwis there, awaiting deportation because of their criminal records, along with several hundred asylum seekers from other countries.
Prime Minister John Key said some of the New Zealand detainees could have been involved in the riot.
"My understanding is that there could be a small number of New Zealanders involved but we haven't been advised of any injuries to New Zealanders," Mr Key said yesterday.
He said if any New Zealanders were involved they could have damaged their chances of successfully appealing against deportation.
"Like a riot at any corrections facility, there may well be consequences," he said.
A coroner will investigate the death of the Iranian Kurdish man on Sunday, named by refugee groups as Fazel Chegeni.
Christmas Island Shire president Gordon Thomson believed Mr Chegeni had "been driven to his death" by his detention.
"He sadly jumped the fence and ran through the dark and fell into a pit and died from his injuries," Mr Thomson told AAP.