FASCIST and nationalist extremist groups are active in and pose a threat to Australia, with the country's security agency saying there are legitimate concerns they may spawn a terrorist in the style of Norway's Anders Breivik.

The assessment, in the Australian Security Intelligence Organisation's annual report to Parliament, also reveals Australia's right-wing extremists, much like the Islamic fundamentalists they loathe, draw inspiration from overseas via the internet.

Anders Behring Breivik. Credit:Reuters

''There has been a persistent but small subculture of racist and nationalist extremists in Australia, forming groups, fragmenting, re-forming and often fighting amongst themselves,'' the report states.

The appraisal also states there has been a recent rise in anarchist or ''anti-fascist'' groups, with the ideologically-opposed groups coming into conflict.