The Abbott government has announced the closure of four immigration detention centres.
Immigration Minister Scott Morrison says the closures will save the government at least $88.8 million a year.
Tasmania's Pontville Immigration Detention Centre, which has been empty since September, will be formally closed.
The Scherger facility in Queensland, the Port Augusta facility in South Australia and the Leonora facility in Western Australia will all be closed by the end of February, Mr Morrison said.
The Pontville facility in Tasmania will also be formally closed after sitting empty since September last year.
Scott Morrison: announced the closure of four detention centres.Credit: Tamara Dean.
Mr Morrison says the remaining detainees in Scherger, Port Augusta and Leonora will be transferred to other facilities in the coming weeks.
He says the facilities were never envisaged as being permanent.
In a statement, Mr Morrison said the detention centres due for closure were "remove, relatively small and expensive".
"Immigration detention facilities within the onshore network are designed to be used flexibly to accommodate a range of detainee cohorts. This principle assumes that when operational requirements change, so too will our use of facilities."
Mr Morrison said that detainees in the facilities would be moved to other detention centres in the coming weeks.
"The savings, which amount to at least $7.4 million a month, comprise the costs payable to the detention services provider, infrastructure and leasing arrangements and detention contractual arrangements,'' he said.
"These facilities were never envisaged as being permanent and due to the rationalisation of the immigration detention network they are no longer required."
Acting Greens leader Richard di Natale said he had "huge" concerns about the Coalition government’s approach to asylum seekers.
“We’ve got a situation where all of our detention centres are under huge strain … and we’re going to close down a number of centres in Australia, move those people [to] where there’s less scrutiny, where tensions are already at boiling point, what do we think’s going to happen?”
Senator di Natale said there would be more asylum seekers self-harming in desperation.
"I think the government’s just got to take a step back," he said.
"Just when you think things can't get any worse, they do."
Fairfax Media understands Labor will not stand in the way of the detention centre closures.
On Tuesday, acting Labor spokeswoman for Immigration Michelle Rowland said that under Labor's PNG resettlement (announced in July 2013), no asylum seekers who arrived by boat were processed in Australia.
"If onshore facilities are no longer being used, it stands to reason that their ongoing viability be assessed in light of current and future use."
AAP, Judith Ireland