Acacia Prison has been in lockdown for the past two days after authorities failed to find the tools used to cut a hole in fencing as part of an audacious plan to break out of the Wooroloo jail.
New details of the plot have emerged, including information mobile phones were smuggled into the prison by the would-be escapees and that mesh had been used to conceal the hole. But the Department of Corrective Services has refused to answer questions from The West Australian.
"An investigation is under way after prison authorities foiled an escape allegedly planned by a number of inmates," a statement read. "Inquiries are continuing into the incident which may affect the normal regime of the prison."
The department said the security breach did not involve a perimeter fence and that the community was never at risk.
But Prison Officers Union secretary John Welch, who visited the privately run prison yesterday, described the hole's existence as extremely serious because it would have enabled prisoners to move between units without guards being aware.
"It is very concerning this was able to take place without anyone having observed it," he said.
He was looking into claims that concerns about breakout plans had been raised with the prison's management about two weeks ago. He said the fence was behind what was known as "Kilo Block".
"The fence is clearly intended to stop people moving between units because that can cause all sorts of problems," Mr Welch said.
It was understood initial searches of the jail, which can hold up to 1000 prisoners, found some inmates had mobile phones. Those inmates have been moved to another jail.
"The worry we have, which we have raised with Acacia management at Serco (the operator) over some time is that they don't have enough staff to ensure safety and security is maintained at all times," Mr Welch said.
Corrective Services Minister Joe Francis said this week the fact that the hole was discovered showed the systems inside the jail worked."I'm not going to go into the operational issues of it, but you can rest assured there was never any threat to the public of these people getting out," he said.