New government data has shown 60 per cent of mental health patients do not get treatment within a clinically recommended timeframe.

President of the Australasian College for Emergency Medicine Dr Simon Judkins said the college was watching the situation in the ACT closely.

"We are mindful that it has taken years of neglect to get to this point, but we are encouraged that the minister is engaged in solving this critical issue," he said.

The data came from Mental Health Minister Shane Rattenbury in response to questions taken on notice in October from opposition health spokeswoman Vicki Dunne.

It showed that in 2017-18, just 40 per cent of mental health patients who came to Canberra emergency departments were seen on time.

While the percentage had been falling since 2013-14 - when 69 per cent of mental health patients were treated on time - the sharpest drop came last year.

The data also showed that while the average length of time people with mental health issues spent in the emergency department before being discharged or sent to a ward had been decreasing, it jumped to 397 minutes in 2017-18, up by 70 minutes from the year before.

In 2017-18, the longest time a patient with mental health issues was left in the emergency department before being sent to an appropriate ward or discharged was 90 hours.

That number increased from 73 hours in 2013-14.

The data also revealed assaults on staff in the adult mental health unit at Canberra Hospital more than doubled last year, even before the final two months of data was added.

In 2017 there were 53 assaults on staff in the ward, but in 2018 up until October 26 there had already been 107 assaults on staff.

In 2012 there were just 12 reported assaults on staff.

Dr Judkins said the college had been outspoken in its calls for improvements to the way people with mental health presentations were managed in emergency departments.

He said it would continue to support patients by advocating for system improvements to provide better health care and outcomes for all patients.

"In the ACT we are watching closely and have had meetings with the Minister and discussions with the CEO of Canberra Health Services," Dr Judkins said.

"Our meetings have been positive and we will continue to work with ACT Health to improve the current situation."

Opposition spokesman Jeremy Hanson said the data showed the mental health ward was at breaking point.

“Patients are waiting too long to be seen and nurses are increasingly becoming the victims of violent assaults, he said.

“Canberrans requiring mental health treatment deserve to be seen on time, and nurses have the right to work in a safe environment.

“The Canberra Liberals will continue to call on the government to urgently upgrade security measures and to explain how they will address blown out wait times in the emergency department.”

The government late last year introduced a nurse safety strategy which it hopes will help stem a rising number of assaults.

It said a change in reporting culture was a contributing factor to the rise in recorded assaults.

A Canberra Health Services spokeswoman said there had been an unprecedented increase in the number of more complex mental health presentations at Canberra Hospital.

She said the hospital was currently reviewing its mental health demand and capacity management.

"This has led to high demand for beds in the adult acute mental health inpatient units so beds are not always readily available," the spokeswoman said.

"Presentations are a combination of those with mental health issues only, and those with a physical illness or injury who are suffering from a related psychological or mental health condition.

"We are also seeing an increase in patients transferred to the ED under an Emergency Assessment Order, and small but growing demand for patients to be assessed on referral from the courts. The Canberra Hospital ED is the only legally approved facility for assessing this group of patients.

"Canberra Health Services began the gradual implementation of a new adult community mental health services model of care in June 2018 in a bid to provide more accessible, responsive, assertive and intensive support in the community."