Australian Nursing and Midwifery Federation ACT secretary Matthew Daniel said it was just one in a string of assaults on nurses within the mental health division in recent months.

The nurse had been assaulted by a patient at the adult mental health unit on Monday night, sustaining cuts, bruises and bite marks to her neck and arm.

He said unnecessary bureaucracy within ACT Health was hampering efforts to make nurses' workplaces safe.

"There's a seeming unwillingness or inability to address the issues at hand," Mr Daniel said.

"The mental health division want to go through all the committee channels ... that's way too long and while that's happening nurses are continuing to be assaulted."

He said the union had previously called on Mental Health Minister Shane Rattenbury to have an independent review of safety within the mental health division.

He said members wanted the executive to stop being "paternalistic" about its approach to staff safety and engage properly with them.

"There has been a long history of a top down approach with staff safety," Mr Daniel said.

Mr Daniel said the union wanted better therapeutic plans for patients at the ACT's secure mental health unit Dulwha, better staffing levels, more security staff, and a better appreciation of the role of mental health nurses.

Mr Rattenbury said he had seen the "distressing" images and said the incident would be thoroughly investigated.

"Our staff should not go home at the end of the day having been assaulted," he said.

"It's quite early days around what happened.

"We do have security staff present in out mental health inpatient facilities in both Dulwha and the adult mental health unit. They are there to provide backup.

"But the primary way to deal with violence is through the clinical approach."

Police, who were reportedly called to the incident, have been contacted and asked if any charges have been laid.

They have not responded.