Reclaim Australia says it has never condoned violence but national intelligence bosses say radical anti-Islamic groups are a growing threat to Australia's security.
ASIO director-general Duncan Lewis said Reclaim Australia, in particular, was of interest to intelligence agencies.
Authorities charged a member of the right-wing group under federal terror laws for the first time in August for allegedly collecting or making documents to prepare for terrorist acts.
Mr Lewis said Reclaim Australia has "offered violence" in the past and expects they will continue to when they confront pro-Islamic groups.
"To the extent that there is a possibility of violence, or there is indeed violence being offered, that is of interest to us. That is business for ASIO," he told a Senate committee late on Tuesday night.
"It is a real problem and it is something that we're very, very acutely aware of and I have people working that particular issue."
But Reclaim Australia said it does not condone violence.
"Reclaim has never condoned violence and we never will. Reclaim has worked closely with police at past events to ensure public safety," a statement provided to AAP said.
Asked by Greens Senator Nick McKim whether the threat from such groups was growing, Mr Lewis said it had - primarily over the last 18 months.
"Yes it is, but I wouldn't describe it as going up in any vertical way. It's come off a low base and it's now more present than it was."
