The man accused of the Christchurch mosque shootings was known within the Australian white nationalist community for three years, the leader of one group says.

The leader of the group has made veiled threats of violence and claimed he tried to recruit the man allegedly behind the mosque attacks on March 15, the Sydney Morning Herald reports.

Lads Society president Tom Sewell approached the accused in 2017, the SMH says.

Sewell said that via an online community he asked the accused to join a project to help create a "parallel society" that was comprised exclusively of white people.

Sewell continued to tell SMH that the group did not condone violence "at this stage" but "if you make the peaceful alternative impossible, you leave only the other option".

The SMH contacted Sewell about comments he and Lads Society supporters made on Facebook after the Christchurch attack.

Sewell had written "this was not a false flag ... take my word for it", according to screenshots obtained by the monitoring group White Rose Society.

Sewell responded to SMH that people within his scene had known about the accused gunman for at least three years.

"The specific correspondence I had with him was that he didn't want to be a member," Sewell said.

The accused was about to travel to New Zealand.

"The difference between my organisation, myself and him, is simply that we believe, certainly at this stage, that there is a peaceful solution for us to create the society we want to live in," Sewell said.

"We want a peaceful alternative, we want to be treated with respect, we want to be left alone.

"If we are not given that opportunity, well, time will tell.

"I'm not going to give you any explicit threat but it's pretty f****** obvious what's going to happen."

Australian Home Affairs Minister Peter Dutton told the SMH that "using violence to force views on others is illegal and unacceptable" and all forms of extremism were being taken seriously.

ANU researcher Jacinta Carroll said that while the group had an extremely small number of supporters, Sewell's language indicated a possible shift towards support for illegal actions such as politically-motivated violence.

"The language used in this interview suggests a simplistic, black and white view of the world based around what this group would seek in an ideal future," Carroll told the SMH.