White supremacists living in Australia have been warned they are "on [the] radar" of authorities, and will face more scrutiny and pressure in the wake of the deadly Christchurch shootings.

Key points: Home Affairs boss warns white supremacists will face greater scrutiny

Home Affairs boss warns white supremacists will face greater scrutiny White supremacy has been linked to the Christchurch mosque massacre

White supremacy has been linked to the Christchurch mosque massacre Mike Pezzullo says the incident was a "horrific slaughter of Muslims at prayer"

Home Affairs secretary Mike Pezzullo made the comments while appearing before a parliamentary committee, one week after a terrorist murdered 50 Muslims worshipping at mosques.

Mr Pezzullo said his department had "rededicated itself to standing resolutely against the extremist ideology of white supremacy and its adherence" in the wake of the attack.

"You are on our radar and you will not be able to incite the racial strife that you seek," he said.

"The scrutiny and pressure you are under will only intensify."

Mr Pezzullo did not elaborate further about the extent of white supremacy within Australia or what greater scrutiny threat would entail.

In a public speech just two days before the Christchurch attacks, Mr Pezzullo identified seven "gathering storms" most likely to threaten Australia's national security, but home-grown right-wing extremists were not included in the list.

He described the massacre as a "horrific slaughter of Muslims at prayer".

"The department has since been working ceaselessly with our colleagues in ASIO, the AFP and other agencies to assist our New Zealand comrades, with the investigation into this unspeakable act and with other elements of the New Zealand government's response," Mr Pezzullo said.

A 28-year-old Australian man is in custody in New Zealand charged with the Christchurch shootings.

When he was taken into court he made a white power gesture. The judge remanded him until April 5.

Extremists told they cannot work for Home Affairs

During a sometimes testy appearance before Senate estimates, Mr Pezzullo was also questioned about reports that a political staffer who helped to write a controversial speech for Senator Fraser Anning is also a Home Affairs Department employee.

According to the Sydney Morning Herald, the man believed to have written the infamous "final solution" address is on leave from the department, which manages Australia's immigration program.

Mr Pezzullo told senators he would investigate the matter but insisted those with extremist views were not welcome in his department.

"Any association with groups that vilify minorities, that either normalise or incentivise violence is completely abhorrent," he said.

"Our duty is to uphold the law and that includes laws in relation to violence, murder and the like."

Senator Anning has been widely condemned in recent days, having attributed the Christchurch attack to Muslim immigration.

His comments have attracted international attention, including the Bangladesh Government issuing a safety warning to its citizens travelling to Australia.