This report was updated at 6pm Thursday 9 March.

Youth Custodial Officers at Western Australia's Banksia Hill Detention Centre have walked off the job following "another insufficient offer" from the Department of Justice that "continues to leave serious workplace health and safety concerns unmet", their union said.

The officers at the youth detention centre are calling on the WA government to meet its responsibility for staff safety and "urgently provide them" with an offer that materially addresses their workplace health and safety concerns.

The CPSU/CSA said its delegates among Banksia Hill staff have been engaged in "almost one year of good-faith bargaining" with the Department of Justice.

"Last night, with overwhelming member support, (delegates) decided to take industrial strike action to call on the government to provide an offer that meets their workplace health and safety concerns, especially after the critical failure of health and safety last week that led to a YCO requiring emergency surgery. The government has this responsibility to all of their public sector workers," the union said in a statement on Thursday.

The CPSU/CSA noted that it has been almost nine months since the last Youth Custodial Officers Agreement expired and members provided the government with their log of claims.

The first offer provided more than one month ago was "overwhelmingly rejected by CPSU/CSA members", and offers since have not seen the safety improvements needed.

"The patience of YCOs is now wearing thin," the union said.

"They have done their part of bargaining in good faith, and turned up to work in an extremely challenging and sometimes dangerous environment, where assaults on youth custodial staff are 100 times more likely than at adult centres. The lack of responsibility from the government on workplace health and safety continues to be unacceptable."

A guard at Banksia Hill was seriously injured during a disturbance in late February, only the latest in a series of incidents at Banksia Hill, a centre which has been condemned by a range of legal and human rights experts.

CPSU/CSA WA Branch Secretary, Rikki Hendon said health and safety have been "at the core" of the claims for Youth Custodial officers.

"A safe workplace for them means a safer Banksia Hill. It is time the government started treating its frontline workers at Banksia Hill with the respect they deserve and stop avoiding their responsibility to workplace health and safety," she said.

"The Department of Justice can enact changes right now, without the requirement for legislative change, budgetary changes or ministerial approval that can meet the workplace health and safety concerns. The Department, and the government, choose not to, choosing to instead endanger their workers.

"Every worker, at every worksite across the state, deserves to go to work and come home safe every single day. That is no less true for Youth Custodial Officers and the Government needs to step up and take responsibility for the workplace health and safety of staff at Banksia Hill Detention Centre."

Young Indigenous people are drastically overrepresented in Banksia Hill and the Aboriginal Legal Service of WA recently slammed the government's management of the facility. ALSWA is working on a number of cases involving complaints from Banksia Hill detainees regarding conditions in the centre.

A State Government spokesperson told National Indigenous Times: "It is disappointing that the CPSU/CSA would take this action with such little notice."

"Banksia Hill's withdrawal of labour plan has been put into place and there is no risk to any of the detainees or the community," he said.

"A revised offer was made to the CPSU/CSA only yesterday during negotiations. The Department of Justice had been optimistic in the light of negotiations over recent weeks that this offer would be received much more positively than the previous one. In that meeting there was absolutely no indication that any industrial action was being contemplated and no notice provided about the action that has taken place.

"We take very seriously our obligations under the Work Health and Safety Act 2020 to take all steps reasonably practicable to ensure safety in the workplace.

"The government has sought urgent help from the Industrial Relations Commission to resolve the terms of an industrial agreement. We understand a conference has been called for 3pm today."

After that conference Banksia Hill Youth Custodial Officers voted to extend their industrial action until 6pm Thursday.

Shortly before 6pm, the WA Industrial Relations Commission ordered the Officers back to work and to "obey any lawful direction" by management.