Corrective Services Minister Joe Francis is concerned that some prison officers have systematically rorted sick and personal leave as he declared the job required "a certain thickness of skin".
Mr Francis has commissioned a review of selection criteria and training for prison officers in a bid to turn around "unacceptable" levels of sick leave, overtime and workers compensation claims.
He said prison officers' overtime and personal leave cost $35 million in 2011-12 - 19 per cent of the total wage bill of $182 million.
This was double the proportion in his other department, Fire and Emergency Services ($14.7 million of $152 million, or 9.6 per cent).
"It is of great concern that we are spending that much on overtime as a percentage of the wages bill," Mr Francis said. "You need to look at this in the context of other Government departments and it clearly isn't right.
"I need to find out why it is so high. I have concerns that leave entitlements could be rorted. Something there rings alarm bells."
Mr Francis said it was hard to prove but there was "anecdotal evidence" that some officers took unpaid, or so-called "purchased" leave, resulting in others working overtime to cover the shifts.
The Department of Corrective Services workers compensation premiums, through Government self-insurance agency Risk Cover, have doubled from $11.5 million in 2010-11 to $23 million in 2012-13.
Commenting on high levels of stress leave and workers compensation claims, Mr Francis said: "There are obviously a lot of dedicated and hardworking prison officers but I would also suggest that clearly some people just may be in the wrong job.
"You need a certain thickness of skin to work in corrections."
The Government's new industrial agreement with the WA Prison Officers Union, to which the union agreed in principle last week, tightens personal leave provisions.
It includes a requirement for statutory declarations on reasons for personal leave and a ban on overtime shifts immediately after absences for illness or injury.
Corrective Services chief Ian Johnson was paid out $420,000 and left the job with three years left on his contract last month and Mr Francis appeared to fire another warning shot at other senior managers.
"Low morale is a culture and leadership issue," he said. "If it is not addressed, it becomes cancerous."
WAPOU secretary John Welch rejected any suggestion of organised abuse of leave entitlements, saying being a prison officer was a stressful job."We absolutely believe our members do the right thing," Mr Welch said.