The use of force and physical restraints in Australia's onshore immigration detention network has soared - more than doubling in just nine months - despite the prison population declining over the same period, internal documents reveal.
Prison officers used "force" an average of 230 times a week between February and April 2016, up from an average of 100 between August and October 2015, according to data obtained under freedom of information laws.
The Department of Immigration and Border Protection defines the "use of force" to include the deployment of mechanical constraints such as handcuffs and flexi-cuffs, as well as any instance where a guard "escorts a detainee by placing a hand on their arm".
In July 2014, force was used just 45 to 50 times a week on average, according to data previously obtained by Fairfax Media. Since, the population of Australia's mainland immigration detention facilities has fallen from about 2400 to 1700 in April, despite the use of force increasing five-fold.
At the same time, the documents show the department has successfully reduced the level of self-harm and violent assaults in mainland detention centres. Instances of self-harm dropped from 146 between August and October 2015 to 88 between February and April 2016.
The department said the increased use of restraints reflected a higher number of "movements" in the detention network, and a growing number of "high-risk detainees" with criminal histories and links to gangs.
"The increase in reporting of 'use of force' incidents does not equate to an increase of aggressive or violent behaviour within the detention network - rather it is the change in the way statistics regarding restraints are recorded," the department said.
"All instances where force is used are reportable - no matter how minor."
According to the DIBP's own analysis, the rates of minor assaults, serious assaults, sexual assault, threatened and actual self-harm have all fallen between 2014-15 and 2015-16.
Natasha Blucher, detention advocacy manager at the Asylum Seeker Resource Centre, accepted the department's advice that most uses of force against detainees are "routine" rather than violent. But she remained concerned that the immigration detention network had become more like the jail system since it was taken over by Australian Border Force in 2015.
Under a policy known as the "enhanced escort procedure", physically and mentally ill detainees are taken to off-site appointments in handcuffs or with a guard's hand on their person at all times.
"The notion of routine use of force is quite concerning," Ms Blucher said. "It results in people being too humiliated or too afraid to go to external medical appointments they need to attend, or people not attending their counselling appointments.
"It can be absurd at times - I've heard of elderly women and people in wheelchairs being escorted with a hand on them."
The "high-risk" population in immigration detention tends to be people who have had their visas cancelled under section 501 of the Migration Act following a criminal offence.
Ms Blucher said there needed to be more flexibility in the risk assessment of detainees rather than treating everyone as a criminal or potential escape. "It's being administered more and more like a punitive detention facility," she said.
The incident logs - covering nine months between August 2015 and April 2016 - were obtained from the immigration department seven months after Fairfax Media first lodged its FOI request.
Unlike the previous occasion on which Fairfax Media requested the same data, detailed summaries of the incidents were redacted from the files supplied by the department. It said the details could be used to identify individuals and were redacted for privacy reasons.