The worsening overcrowding crisis at the ACT's main prison has forced the government to send more inmates to the temporary Symonston jail.
The full-time prison at Symonston was opened this year to help take overflow from the overcrowded Alexander Maconochie Centre until permanent capacity upgrades come online.
The government had said it would be used to house only 22 detainees, and only those that posed the lowest risk.
Now, Corrections Minister Shane Rattenbury has revealed the government has been forced to send more detainees to the temporary facility. It has added eight new beds, taking the capacity to 30, and moved in six more detaineess, taking the total to 28.
He said he was reacting to growing overcrowding pressures at the prison, saying the ACT had recorded its highest ever number of detainees in recent weeks, with 374 people held by Corrective Services.
"The decision to move more detainees to Symonston has not been taken lightly," he said in a statement.
"However for the safety of staff, detainees and the good order of the ACT's correctional facilities it is important that we maintain manageable numbers within the AMC and this means moving additional detainees today."
The first permanent capacity upgrade at the prison is expected to come online in the latter half of 2015, adding 30-beds. It is hoped this will significantly relieve population pressures.
A larger expansion is expected to be completed in mid-2016, bringing another 110 beds, with additional surge capacity.
The upgrades were announced in late 2013, as the government grappled with fitting soaring prisoner numbers into the relatively new prison.
At the time of its construction, experts warned the government to expect the kind of numbers it is now experiencing.
That advice was not heeded, and the government produced its own prisoner population modelling, using it to justify the construction of a smaller, cheaper facility.
Mr Rattenbury said the problem of overcrowding was not isolated to the ACT, and said a recent conference of corrections ministers showed other jurisdictions were facing "unprecedented population pressures".
The six detainees are expected to be transferred to Symonston on Tuesday.
The use of the facility sparked some concern by the local residents' association, the Inner South Canberra Community Council.
Members fear the Symonston facility may become permanent, something nearby residents were never consulted about.
Chairman Gary Kent said residents feared the eight extra prisoners could be a sign the facility's population would continue to grow.
"We always understood it would be 22 specially-selected, low risk prisoners," he said.
"We are disappointed that it has gone up to 30 though we understand the reason why and the minister has been up front about that.
"While [residents] are accepting, they're not happy. We still have residents who are very unhappy they're living next door to a jail."
Mr Rattenbury had assured residents the Symonston facility would be closed to prisoners as soon as the initial AMC upgrade was complete and they would seek to hold him to his word, Mr Kent said.
Residents were made aware of the additional detainees before Mr Rattenbury's announcement.
He said the community's doubts were largely based on security matters that included a risk of prisoners escaping, proximity to homes and The Farmyard Nursery.
There were also concerns about structural aspects of the prison, such as bright lighting.
"We understand the work at the AMC is on time but we don't want to see a facility that grows and grows over weeks and months and years.
"It would be completely unacceptable to the local community."
Roughly $60,000 was spent on preparing it as a full-time prison, a move announced in early April.
The first detainees went there in June. The first cohort of 10 prisoners immediately filled up a large portion of the Symonston facility, taking up almost half the space.