Prison guards across NSW will soon be taught to spot radical extremists trying to influence other inmates behind bars.
Home Affairs Minister Peter Dutton said there were already roughly 30 people in prison for terror-related offences and scores more before the courts, including three juveniles.
"We're worried about people radicalising in the jail setting," Mr Dutton told 2GB radio on Thursday.
He said the threat posed by Australia's small but increasing population of convicted terrorists did not necessarily end with locking them up.
"We don't want them spreading their evil message in jail," Mr Dutton said.
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Roughly 5000 corrections and juvenile justice staff will be trained through the national "radicalisation and extremism awareness" program, which already operates across other states and territories.
"If people think we're dealing with petty criminals - even the description of juveniles is misleading when you've got somebody that wants to go out there and kill Australians in big numbers," Mr Dutton said.
"We need to be realistic about the threat and that's why we're supporting the NSW government."
NSW Corrections Minister David Elliot said the program would complement the state government's investments in upgrading its Supermax prison and creating a new high-security unit for high-risk inmates.
"The highest priority of any government is to keep our community safe from those who would do us harm," he said in a statement.
