Nick Kaldas, a former NSW Police deputy commissioner and now a senior fellow at the Australian Strategic Policy Institute, said the growth of right-wing extremists had not been adequately monitored.
"It has been clear for some years that there is a lot of activity in the right-wing group space,'' Mr Kaldas told The Australian.
"It's incumbent on authorities now that the threat has become so visible that they change tack and dedicate more resources to monitoring that type of group.''
It comes as Victorian Police revealed dozens of right wing extremists are on terror watch lists, and monitoring of the so-called alt-right has escalated after the deadly attack in New Zealand by an Australian.
Chief Commissioner Graham Ashton on Sunday said police were keeping tabs on the Victorian extremists, particularly online.
"After Friday we have intensified our monitoring of the alt-right individuals within Victoria," Mr Ashton said.
"We've been monitoring also a range of individuals since Friday, we're just making sure we're not seeing any increased levels of anxiety around any sort of action and certainly to date we haven't seen that."
Mr Ashton said he spoke with his federal counterpart about monitoring online rhetoric that might constitute a federal offence.
"These threats can emerge very quickly and often from very little information or intelligence beforehand," he said.
"You do the best you can, we make sure we're plugged into what's happening in the intelligence arena, particularly with our federal partners."
Mr Ashton was at Preston Mosque on Sunday alongside Premier Daniel Andrews as part of a pre-organised, statewide open mosque day.
Anti-immigration white nationalists violently leapt on a teenager who egged Queensland Senator Fraser Anning at an event in suburban Melbourne on Saturday.
Among them was convicted criminal Neil Erikson who is currently going through the courts again.
Mr Ashton said he's directed his officers to go through footage of the incident in its entirety to consider whether assault charges and breach of bail offences might also come into play.