Staff at Borallon Correctional Centre are being put at increasing risk due to overcrowding at the prison, the Together Union says.
It comes just days after a violent attack by an inmate on two prison officers at the facility near Ipswich.
Together Union's Michael Thomas said a prisoner had armed himself with a make-shift weapon and attacked an officer but managed to subdue the inmate.
"It's another stark reminder of how dangerous prisons can be," he says.
One of the officers is now recovering from cuts and a puncture wound to his head while the other, who suffered a head knock, has returned to work following the incident on Wednesday.
Queensland Correctional Services has put out a statement confirming that two officers were injured in an incident but disputed any use of a stabbing implement.
"Officers were conducting a unit inspection when a prisoner approached an officer and punched him. At no stage were any officers stabbed," the statement reads.
"The officer attempted to move away from the prisoner, who continued to approach him before responding officers subdued the prisoner and he was removed to the detention unit.
"One officer received a cut to his chin from the incident and was assessed at the medical centre and then went off duty.
"The second officer was assessed at the centre following the use of force but remained on shift."
Mr Thomas says Borallon, like many Queensland prisons, is beyond 100 percent capacity with two inmates double bunked in a cell.
"We've certainly seen increases in assaults in recent years because of overcrowding," he says.
"At the moment there are units with up to 80 prisoners, there's only two staff.
"There's response capability outside that, but for those two staff you're in a state of constant vigilance and constant concern that you're the next one going home via an ambulance to hospital."
Image: Borallon Correctional Centre, AAP/Jono Searle