Dozens of Australian jihadis have vanished in Europe after fleeing the conflict zone in the Middle East.
Ross Guenther, the Victorian counter-terrorism chief, confirmed high numbers of fighters who were due to return home following terror campaigns in Iraq and Syria remain unaccounted for.
Assistant Commissioner Guenther said it was challenging to determine where many of the fighters had landed, before adding it was testing in some places to penetrate borders.
Speaking at the unveiling of Victoria's counter-terrorism blueprint,MrGuenther said there was currently limited intelligence when it comes to the whereabouts of fighters and the exact number involved overseas.
'We believe there's a number of Australians still in the Middle East or in Europe,' he said.
'We expected quite a few of these would have made their way back, but that hasn't been the case at this point in time.
'It could partly be because it's very difficult to cross the border there or because they have passed across other borders into western Europe.'
The chief focus of the Victorian counter-terrorism strategy is education.
'Prevention is far better than cure and we are committed to stopping people from seeking to engage interroristbehaviour,'MrGuenther said.
'In the past year, we've seen the establishment of the fixated threat assessmentcentre, which gives us the opportunity to have police and mental health professionals work together to manage potential threats from fixated persons.'
Neil Prakash is regarded as Australia's most infamous Islamic State terrorist.
Born in Melbourne, the ISIS member was believed to be dead, only to be captured in November of 2016 attempting to cross the Syrian border into Turkey using false documents and a fake name.
Prakash is currently on trial on terrorism charges.
He will not be returned to Australia until his current legal proceedings, as well as any imposed jail term, are completed.