Prime Minister John Key said it was likely New Zealanders were involved in the riots, but he did not have official confirmation of that. "My office has had an update...we're obviously aware of what's taking place there. It's a difficult situation to get all the facts on," he said. "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."
Riot police have stormed the embattled Christmas Island detention centre, allegedly using gas canisters and rubber bullets to restore order.
It is understood the guards entered the facility around dawn on the island.
There were reports of some detainees barricading themselves inside with petrol bombs, machetes and chainsaws after raiding a garden shed for weapons.
The unrest began in the early hours of Monday morning after upset refugees asked officials what happened to refugee Fazel Chegeni, whose body was found on Sunday following his escape from the detention centre.
The detention centre is run by controversial private prison operator Serco, which hit headlines in New Zealand this year after a series of scandals emerged at Mt Eden prison.
Two bus-loads of guard reinforcements were trucked to Christmas Island overnight, patrolling the perimeter of the centre, as sirens sounded for hours on end.
Labour corrections spokesman Kelvin Davis said some of the detainees had barricaded themselves in their compound and were "terrified".
Christmas Island detention centre. Photo / Getty Images
"They said 'They're coming in'. Gas canisters have been allegedly fired off, rubber pellets have been allegedly fired off. One guy claims to have been hit in the leg by one...the guys that I spoke to were in their cell, barricading themselves and keeping themselves safe. "It was pretty chaotic, there was a lot of noise in the background.
"It could be all over by now to be honest, it was a David versus Goliath situation. I just hope everyone's OK."
Other detainees said the sprinklers had been turned on and were flooding the compound. "The riots squad's all geared up ready to come in. Everything's barricaded up, all the young fellas are all tooled up.
"They've got petrol bombs, they've got machetes, they've got chainsaws, metal bars all sorts," Kiwi detainee Tuk Whakatutu told Radio NZ.
Earlier Mr Davis said the men inside were bracing for a fight.
"One of them said to me: 'I'm not going to throw the first punch. If they come in, I'm going to let them hit me but I'm going to hit back'. It was almost like he was going off to battle and not expecting to come back.
"I'm picking that come 3am or 4am in the morning when the detainees are at their very lowest ebb, they'll be attacked by riot squads."
Prime Minister John Key said it was likely New Zealanders were involved in the riots, but he thought there was a danger they would damage their own appeals.
"My concerns would be that, like a riot at any corrections facility, there can and may well be consequences as a result."
New Zealand detainee Lester Hohua said the rioting at Christmas Island Immigration Detention Centre had been brewing.
Over-crowding and alleged assaults by the emergency response team (ERT) had put the detainees, including about 40 New Zealanders, at breaking point, he said.
"It was just a matter of time, all of us knew it. It was a matter of time because of the way they treat people," he told NZME News Service.
"We're Kiwis, we're not bred for the psychological trauma...This is what war-torn country people [see], it's not for us."
Authorities confirmed an "operation" was underway to restore order at the centre today, stating some of the detainees were still resisting.
Australia's Department of Immigration and Border Control said staff were negotiating with detainees "engaged in protest activity" and were gradually securing control of the centre.
Some detainees who were not involved in the "disturbance" were moved to a secure part of the centre last night.
"However, a group of detainees are continuing to engage in non-compliant behaviour putting themselves and others at risk.
"The department and its service providers remain committed to resolving the situation peacefully and quickly, but will take action to protect people and facilities where an imminent threat exists," the department said.
News of the action comes as Australia is facing a grilling over its human rights record, appearing in the hot seat before the UN Human Rights Council for a performance review on Monday.
Amnesty International had urged New Zealand to speak out on its neighbour's "abysmal" record, in particular its policies for asylum seekers.
But Prime Minister John Key said yesterday New Zealand did not plan to do so.
"I don't think the Australians would accept that there are human rights issues and from New Zealand's point of view we have said that we will investigate any that are brought to our attention."
Mr Key said he had been told that detainees faced a wait of "weeks, not months" before they could return to New Zealand.
Justice Minister Amy Adams said she was seeking reassurances from her Australian counterparts that they would help Kiwi detainees return home as quickly as possible.
She said Australian Prime Minister Malcolm Turnbull had assured her New Zealand detainees could return home, their applications would be handled "expeditiously", and their return to New Zealand would not be detrimental to their appeals against deportation.
