Peter Dutton has confirmed that a group of detainees have been transferred to Christmas Island.
A group of detainees were transferred from the Maribyrong centre in Melbourne on Wednesday night.
The Immigration Minister confirmed reports on Thursday, telling media in Canberra that 35 people were involved in the movement and 23 were moved to Christmas Island.
"Overnight, a number of people have exited those detention centres and have been taken to Christmas Island where there is a more hardened environment in terms of those people," he said.
Mr Dutton said the composition within centres had changed, with more people now in detention after having their visa cancelled on "grounds of character".
"We have people with significant histories who are in the detention centre network," he said.
Mr Dutton said asylum seekers were among the people involved in the movements on Wednesday, but the majority visa cancellations and people "on a pathway to exit" Australia.
He could not provide a number regarding asylum seekers.
"Some of those people have quite extensive criminal histories, so in the case where somebody has committed murder, where they've submitted a sexual assault or an armed robbery, a serious crime, at the end of that custodial sentence they in some cases will move into a detention centre awaiting their return to their country of birth," he said.
Speaking to media earlier, Mr Dutton cited no tolerance laws for detainees, saying that the population within detention centres were “hardening”.
He said that authorities would move people within the detention centre network to “more hardened facilities” if required for security reasons.
“The population mix is changing,” he said.
“I've sent a clear message to people at Villawood, at Yongah Hill, if you act outside the law, if you threaten guards or destroy property or harm people who are fellow detainees, there will be a zero tolerance approach to that and we want the rule of law to operate in our detention centres as it does in society.”
His comments follow a raid at the Villawood Detention Centre, which saw five people removed after a reported 24-hour ice-fuelled rampage.
Mr Dutton told reporters that no ice had been found at Villawood or other detention centres, stating that the government wants "integrity within the network".
He also commented on recent work by immigration officers, who netted 38 illegal workers during raids on horticulture businesses.
