Surging detainee numbers have put enormous pressure on overcrowded prisons across Australia, including the AMC, which has undergone urgent capacity upgrades to cope.

A 30-bed special care centre, opened on September 22, was hoped to help alleviate pressures on housing and separating inmates at the AMC, until a larger, 56-cell block is completed next year.

But numbers provided to Fairfax Media show the care centre was already full in October.

The centre is split into three 10-bed wings, designed for different types of rehabilitation, treatment programs, and complex needs.

In October, an average of 31 detainees were held in the 30-bed centre. The situation worsened in November, when an average total of 46 detainees were housed in the care centre.

To cope, 13 extra beds were installed in two of the wings by mid-December. A process of "double-bunking" is still underway, and is expected to be completed in January.

The cells were originally built and designed to accommodate doubling-up, but corrections authorities were hoping not to have resorted to it so soon.

Corrections Minister Shane Rattenbury said the special care centre, with its flexible accommodation design, was proving valuable in helping to deal with overcrowding in the broader prison.

The key issue for corrections in dealing with accommodation issues was separation – keeping inmates separate from others for their own safety.

"What having a special care centre has allowed is a greater level of flexibility, in terms of where people can be placed, and how they can be grouped," Mr Rattenbury said.

"That's certainty been very beneficial in the day-to-day running of the jail."

The centre is said to already have contributed to better rehabilitation course completion rates, and an improved culture of positivity and cohesion among its residents.

It has its own program and interview rooms, meaning that certain prisoner types – those who are often targeted behind bars – can live in the same place they undergo programs.

Mr Rattenbury said that meant they did not have to be walked through the broader prison, something that can be counter-productive.

"We want to make the maximum use of it, and I am happy to do that from day one," he said.

"It is designed to deliver a certain kind of care for people: it is designed to have cohorts of people together."

Part of the special care centre, the "complex needs" wing, is also used as a step-up or step-down facility for the crisis support unit, where detainees with mental health issues or self-harm risks are treated.

That wing appears to be under less pressure than the other two in the special care centre.

Similarly, the crisis support unit has managed to remain free of operational pressures in September, October, and November.

The CSU, a 10-bed unit, was full for only three days in the entire three month period, according to government figures.

Shadow Corrections Minister Andrew Wall said the government had been unable to ensure the AMC had proper capacity since the jail opened back in 2008.

"Every time new capacity is added, demand outstrips supply before new spaces come online," Mr Wall said.

"This is leading the government to consider diversionary measures such as community corrections orders which will see criminal offenders who would otherwise be in jail, out in the community."

To better cope with overcrowding, a temporary full-time prison was opened in the Symonston correctional centre.

That unit was designed to only be operational while the permanent upgrades to the AMC were completed.

Resident groups are closely watching the situation, and say they will be angered if the temporary Symonston facility is used in a permanent fashion.