The funding injection is aimed at bringing the general-purpose population in the prison up to 1782 in four years, with 512 new beds across four units already under construction and another 344 beds planned.

“The Casuarina expansion, including the 512-bed project and the subsequent 344-bed project and related infrastructure upgrades, will create more than 2000 local jobs and will create significant opportunities for local businesses,” a statement said.

Mr Logan said the Casuarina expansion meant the state government could begin to clean up the “mess” of the corrections portfolio.

“It was appalling mismanagement by the previous Liberal National Government that Western Australia’s prison estate had virtually no short, medium or long-term plans in place,” he said.

“The prison estate was in such a mess when I took on this portfolio that the only solution put forward was to simply put more prisoners in the same amount of cells.

“If we had not acted by using existing prison land to build in a smarter and more efficient way, then our prisons would have been over capacity in just a handful of years.

“By having a long-term custodial infrastructure plan in place, it not only gives the government future options but will help guide future planning and provide a direction for bringing Western Australia’s prison estate back under control after years of neglect.”

The plan comes two years after the most recent inspection of Casuarina Prison by Inspector of Custodial Services Neil Morgan, who last reported on the facility in August 2017.

At that point, Mr Morgan noted the prison was “stretched at almost every point”.

"It was never built to hold so many prisoners, and is not resourced to properly meet the needs of both a remand and sentenced population,” Mr Morgan said.

Mr Morgan called for better justice planning and for a clear plan for Casuarina.

"We can't just keep adding more people into existing facilities without doing more to meet their needs in relation to mental health, rehabilitation and post-release support,” he said.

Mr Morgan highlighted the limited infrastructure and resources at Casuarina had meant a severe backlog for prisoners in many aspects of the prison's logistical functions, and said shared cells were of particular concern.

The announcement also comes just a week after Mr Morgan released a damning report into Hakea Prison, finding it is "over-stretched, overcrowded, and overstressed".

Mr Morgan said the prison was too small and no longer fit for purpose with infrastructure deficits and overcrowding meaning conditions were "not decent or humane".

He said prisoner-on-prisoner assaults seemed to have increased since mid-2018, with a number of serious recent incidents.

"The crowded conditions make it extremely difficult for the prison to manage the different prisoner cohorts, and the forced doubling up of single cells adds to the risk," he said.

"The problems were compounded by regular staff shortages, and excessive 'lockdowns' and 'barrier management'.

"Despite some positive efforts by management, staff/prisoner relations had declined, prisoners felt more unsafe, and access to recreation and other activities was severely restricted."

Mr Logan reiterated there was no quick fix to overcoming years of underinvestment by the previous Liberal-National Government.

The WA Prison Officers Union has been contacted for comment.