The Federal Greens want to set up a new national organisation to prevent beheadings and other brutal terrorist attacks happening in Australia.

The Centre For Social Cohesion would bring together police, spies, academics, community leaders and former extremists.

Its job would be to reach out to young people and stop them becoming radicalised or influenced by international terrorist groups like Islamic State (IS).

Greens leader Christine Milne told AM potential terrorists only turn to violence because they "feel alienated" from Australian society.

"Before we say potential terrorists, what we're talking about is young people in Australia ... who might be feeling really isolated, angry and vulnerable," Senator Milne said.

"They feel alienated and then they are attracted to a group, whether it is an extremist group, in terms of a gang, or whether it is a jihadist group."

The centre would be independent, would work closely with the Islamic community and other groups, would advise governments and identify gaps in counter-terrorism research.

The Greens plan to introduce a bill to the Senate to try to set it up.

The party has not discussed the proposal with the Government or Opposition and it seems unlikely to be supported.

"When it comes to acts of terror in Australia, prevention is much better than cure," Senator Milne said.

"This disgraceful ban-the-burka campaign has made people feel as if they don't share the same aspirations as other Australians."

The Government has allocated $13.4 million to community outreach programs as part of its $630 million counter-terrorism package.

"That's a mere 0.5 per cent of that total budget. It is not the priority it needs to be," Senator Milne said.

"[We need] an independent national body because there is often a fair bit of scepticism and suspicion about government agencies.

"Young people tend to view them as having a vested interest."

The Greens have opposed several parts of the Government's new national security laws and have been the most vocal opponents of Australia's military involvement in Iraq.