Violence in the Queensland prison system has reached a new high, with almost 3,000 jailhouse assaults recorded last financial year.

Key points: Queensland prison overcrowding flagged as the biggest operational issue

Queensland prison overcrowding flagged as the biggest operational issue Attacks inside prisons have been steadily on the rise since 2013/14

Attacks inside prisons have been steadily on the rise since 2013/14 All the state's high security prisons are over capacity

Video obtained by the ABC reveals the ferocity of some of the attacks.

In one, a prisoner in Maryborough is set upon by three inmates while chatting to other prisoners on a set of stairs.

The beating leaves him unconscious, and his companions leave him motionless on the stairs while dozens of other prisoners casually walked past him.

Most of the 2,997 attacks in 2017/18 were prisoner on prisoner, but 284 of those assaults were on prison staff, the highest on record.

Another video recorded on a prison guard's bodycam shows a prisoner being served a meal in his cell and then, without warning, throwing a punch at the officer, striking him in the face.

A scuffle knocks the camera off as guards pile into the cell to subdue the inmate.

Sorry, this video has expired A 2017 attack on a prison guard at Brisbane Correctional Centre

Such attacks are part of a 131 per cent increase in assaults since 2013/14, revealed in the analysis of Custodial Incident Reports published each month.

The trend has prompted Queensland's new Corrective Services commissioner Peter Martin to declare prison overcrowding to be his biggest operational issue.

Overcrowded prison cells are regarded as a major cause of tension among inmates.

Over that same four-year period, prisoner numbers have also risen dramatically.

The imprisonment rate has risen every year as courts send more offenders away and successive governments express a tough-on-crime approach.

As a result, every high security correctional centre in Queensland is over capacity, meaning they have more prisoners than beds.

The solution has been "doubling up", which typically involves laying a mattress on the floor of a single cell to allow it to house two inmates.

Sorry, this video has expired See inside a 'doubled up' prison cell

Mr Martin recently walked the ABC through Brisbane Correctional Centre, currently running at 142 per cent capacity.

The 49-bed cellblock he showed us currently houses 73 prisoners.

"This is a typical cell," Mr Martin said pointing through a metal door into a concrete room about three metres square.

Queensland prison pressures Assaults more than doubled from 1,298 in 2013/14 to 2,997 in 2017/18

Assaults more than doubled from 1,298 in 2013/14 to 2,997 in 2017/18 Prisoner numbers rose from 6,076 in June 2013 to 8,900 in June 2018

Prisoner numbers rose from 6,076 in June 2013 to 8,900 in June 2018 Capacity rose from 90 per cent in 2012/13 to 124 per cent in 2017/18

A single bunk was against one wall while a toilet and open shower cubicle cover the other wall.

In between, a desk under a window supported a small television in a clear plastic case (which allows guards to check it for hidden contraband).

A mattress took up almost the remainder of the space on the floor.

Mr Martin shuffled over the floor to stand between the mattress and the toilet.

Anyone lying on the mattress could reach out and touch the toilet.

"Picture the early hours of the morning — the prisoner getting up to use the convenience, stepping over somebody and using it right there within literally half a metre from somebody's head, that's the reality," he said.

"And this is happening in correctional centres right the way across Queensland."

A typical cell "double up", a significant source of tension in Queensland prisons. ( ABC News )

The Together Union, which represents prison guards, has told the Crime and Corruption Commission that in some jails there are insufficient facilities for all prisoners to sit down to eat at the same time.

Mr Martin agreed the close proximity of inmates caused ongoing tension.

"There is no doubt about that at all, and in cases where that occurs there've been assaults, been fights between prisoners and in some cases spilled out into the safety of the prison officers," he said.

"So it's something we are very, very concerned about.

"In fact, in terms of the operational issues, it's my number one priority to address the issue of overcrowding."

But Mr Martin would not say whether he had asked the State Government for more money to build more beds to get prisons back to his department's own benchmark of 98 per cent of capacity.

"It'd be really inappropriate at this stage to dive into the detail of that but to say we are really having sensible conversations," he said.

But for some, building more prisons is not the answer.

Attacks on prison officers have risen to a record high. ( ABC News: Melanie Vujkovic )

'Too many people are dumped in prison'

Debbie Kilroy from prisoner welfare group Sisters Inside said prison capacity was the wrong argument.

"You only see the Corrective Services commissioner come out and say they are worried about it when they want to build their empire," she said.

"They didn't care five years ago when women were sleeping on the floor. Nothing is being done about reducing incarceration.

"We have to look at the social issues pipelining people into prison.

"Nothing is changing other than the prison system gets bigger and they're doing nothing about people dealing with homelessness, mental illness, with addiction — they're just being dumped in prison.

"Prisons have become the new mental health institutions."

Opposition Corrective Services spokesman Trevor Watts called for better rehabilitation programs to keep repeat offenders out of jail.

"Staff deserve not to be thrown into a cage fight, the prisoners deserve not to be overcrowded," Mr Watts said.

"Overcrowded prisons will lead to violent prisons, and violent prisons will mean that when people are released, they're not rehabilitated."

In a report published earlier this year, Human Rights Watch found people with disabilities, particularly cognitive or psychosocial disabilities, made up almost 50 per cent of people entering prison.

Documents obtained by the ABC through Right to Information also showed prisons were prolific buyers of psychiatric medication.

In 2016/17, seven prisons — Brisbane, Brisbane Women's, Capricornia, Lotus Glen, Maryborough, Wolston and Woodford — spent a total of $658,676 on medicines to treat mental illness.

This is more than Gold Coast Hospital spent in the same year ($512,602.51) and just less than Townsville Hospital ($680,125.38).