A sociologist says the threat of far-right extremism hasn't gone away.

It's almost a year since the Christchurch terror attacks, in which 51 people lost their lives at the Al Noor and Linwood mosques.

Massey University professor, Paul Spoonley, told Andrew Dickens between 150 and 300 core right wing activists remain in New Zealand - which puts us in line with Germany per capita.

'Let's keep it in perspective, the numbers are actually quite small in New Zealand.

But as long as there's one of them, we should be concerned, because as you saw on the 15 of March last year, it only takes one person."

Sunday's memorial service is going ahead - but has been moved to Christchurch's Horncastle Arena because rain is forecast.

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