The head of the Australian Federal Police has warned that the threat of terrorism in Australia is getting worse, after confirmation that a 12-year-old is among a group of radicalised youth on the police radar in connection with the Parramatta shooter.

Key points: AFP confirms 12-year-old linked to Parramatta shooter

AFP confirms 12-year-old linked to Parramatta shooter Commissioner says threat of terrorism in Australia is worsening

Commissioner says threat of terrorism in Australia is worsening Warns of 'over-policing' in earlier stages of intervention

The comments by AFP Commissioner Andrew Colvin come ahead of a summit called by Prime Minister Malcolm Turnbull that sees police and intelligence chiefs from the states and territories, as well as the AFP and ASIO, gathering in Canberra today.

Education department chiefs were also brought in, as part of efforts to combat extremism among young people.

It follows growing concerns about the number of young Australians being radicalised following the murder of a police employee by 15-year-old boy Farhad Jabar outside Parramatta police HQ.

Last night's 7.30 revealed a 12-year-old boy is being watched by police because he is part of a group of extremists who may have helped the 15-year-old shooter.

Mr Colvin told 7.30 the issue of terrorism was becoming more difficult to manage.

"We're shocked that a 12-year-old is on the police radar for these type of matters," he said.

"Yes, the problem is getting worse for Australia, not better.

"The numbers of individuals that we're concerned about overseas has plateaued a little, as the Foreign Minister has said.

"Some very good work is being done by our border agencies and our police and security agencies to stop people from leaving for the conflict zones, but there's no doubt that this problem is becoming more acute and more difficult."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 5 minutes 50 seconds 5 m These are the young men behind the Parramatta gun plot and what police knew about them

He stressed there was the risk of "over-policing" on the issue and that early intervention without the involvement of police officers would help reduce the risk to the community.

"Obviously police will always have an important role to play because ultimately we carry the responsibility of ensuring the safety of the community," he said.

"But before police are involved, there's many things that we can do to intervene at earlier stages and that may not involve police.

"We have to be careful to find the balance and make sure the community understand what we're doing and work with them because, as we keep saying, police cannot be everywhere, we cannot watch everyone."

Justice Minister Michael Keenan told the ABC there would be no Muslim community representatives at today's meeting, but the Turnbull Government was a "government that seeks to be good for them".

Mr Keenan said the meeting would discuss issues within prison systems, one part of the current radicalisation challenges.

He said the news of the 12-year-old boy being monitored by authorities was systematic of the challenge.

"We know ISIL has been grooming young Australians," he said.

"Initially they started with people in their 20s, then moved on to people in their late teens, and we're now seeing them move onto people in their early teens.

"It shows you the difficulty for our authorities in facing up to this challenge in what is a difficult and heightened terror-threat environment.

"We don't know where bottom's going to be. Obviously we're very concerned and that's why we're holding this summit today."

Greens say Government spends 'overwhelmingly' on policing

In a statement, Mr Turnbull said the most effective defence against terrorism was preventing someone from becoming radicalised in the first place.

"It is important that as a community we are alert to young people who may be heading down the dark path of radicalisation and take action as early as we can," he said.

He promised any ideas would be considered by the Council of Australian Governments (COAG) later this year.

A spokesman for Opposition Leader Bill Shorten said Labor had requested an invitation to the meeting in Canberra but had been knocked back.

"Given the seriousness of the issues being discussed, we had hoped the Government would see this event as above politics," the spokesman said.

Greens leader Richard Di Natale welcomed the new focus on social programs to prevent young people being radicalised.

"There has been a disproportionate focus on the law enforcement end," he said.

"A lot of that is really to create the impression the Government's acting. I think it's misplaced," he said.

The Greens plan to ask questions in Senate Estimates next week to try to determine where the funding for countering violent extremism has been spent.

"I suspect what we'll find is the overwhelming spend has been on policing and nowhere near enough has been spent on building social cohesion," Senator Di Natale said.