New South Wales Police have named the rise of white supremacist groups as one of the main threats to social cohesion in Australia.

Police Deputy Commissioner Nick Kaldas said a number of organisations fitting that description are moving out of the shadows.

"Racist groups who have in the past worked under the radar, coming out, spreading hatred, particularly on the far-right," he said.

Mr Kaldas said police were watching the trend closely although he declined to name any specific groups.

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"I'm loathed to give them any oxygen but I would say that there is definitely activity on the right wing, the extreme right wing, of politics and people who are using events around the world to create incidents in Australia and NSW and in Sydney," he said.

"We're not taking our eye off that ball. We are watching it just as much as we watch anybody else."

He was speaking today at a community cohesion conference at the University of Western Sydney, in Parramatta.

'Online mobilisation' contributes to growth of extremism

Race Discrimination Commissioner Dr Tim Soutphommasane also gave a speech, in which he echoed the concerns of police.

"It's of concern that extremist organisations are being emboldened and conducting their activities in public more frequently and more visibly," he said.

"Part of it must have something to do with online mobilisation, the fact that you can attract attention and support more easily through social media and the internet."

Dr Soutphommasane said he is happy with the police response so far, but he warns that Australian white supremacists may become even bolder in the future.

"Vigilance is going to be important here and we need to ensure that we monitor developments closely and that there isn't an escalation in the situation," he said.

"The last thing we would want to see is physical violence involving racism in our streets and in our suburbs."

He said national unity is the best response to violent extremism, no matter its persuasion.

"The best antidote we have is for a cohesive and harmonious society where people can feel that they belong to Australia, where they don't have the need to repudiate our society and it's institutions and values," Dr Soutphommasane said.