The Morrison government has banned Milo Yiannopoulos from entering Australia after the controversial right-wing commentator responded to the New Zealand mosque massacre by describing Islam as a "barbaric" and "alien" religious culture.

The ban will be the third position the government has held in as many weeks on whether to allow the controversial figure to travel to Australia for a speaking tour later this year.

Milo Yiannopoulos. Alex Ellinghausen

In early March, senior Coalition figures supported a preliminary Department of Home Affairs plan to deny Mr Yiannopoulos a visa, before backflipping three days later amid a backlash from some Liberal Party MPs and conservative media outlets.

That decision was reviewed on Saturday morning following Friday's terrorist attack at two mosques in the New Zealand city of Christchurch.

Australian citizen Brenton Tarrant is alleged to have killed at least 49 people and injured up to 50 others in a rampage using semi-automatic weapons he legally purchased in New Zealand.

Video captures the moment a suspect was arrested in Brougham Street after the mosque shootings in Christchurch.

The Morrison government rushed to review the future of Mr Yiannopoulos, who has a history of attacking Muslims, after he used an overnight Facebook post to claim assaults like the one in Christchurch happen because the establishment "mollycoddles extremist leftism and barbaric, alien religious cultures".

He also defended right-wing commentator Candace Owens after Tarrant wrote in a manifesto that the conservative American political activist was the person who "influenced me above all".

"Each time she spoke I was stunned by her insights and her own views helped push me further and further into the belief of violence over meekness," Tarrant wrote.

In a Facebook post overnight, Mr Yiannopoulos said Owens had "nothing to do with what happened" in New Zealand and appeared to blame the left for the deadly assault.

"People aren't radicalised by their own side. They get pushed to the far-right by the left, not by others on the right," Mr Yiannopoulos wrote in a post that has since been shared widely.

"Attacks like this happen because the establishment panders to and mollycoddles extremist leftism and barbaric, alien religious cultures. Not when someone dares to point it out."

Mr Yiannopoulos noted in the post that he rejected political violence.

The government was appalled by Mr Yiannopoulos' response to the New Zealand terrorist attack and will make a formal announcement about the ban on Saturday afternoon.

Earlier, Labor frontbencher Tony Burke said: "Surely the Liberal government is still not going to issue a visa to someone so he can conduct a tour to promote hatred against Muslims."

A letter sent to Mr Yiannopoulos by the Department of Home Affairs earlier this year noted the Migration Act gave it the power to refuse a visa application in the event the person would "incite discord in the Australian community or in a segment of that community".

In addition to citing violent protests during his last major Australian speaking tour in Melbourne in 2017, the immigration officials also specifically noted Mr Yiannopoulos had made controversial statements in relation to minority groups including Muslims.

Senior members of the government were satisfied with the decision to block Mr Yiannopoulos, but Immigration Minister David Coleman intervened last weekend to personally approve the visa.

At the time, a government source said Mr Coleman strongly disagreed with many of Mr Yiannopoulos' views and statements but had reached the view that someone should not be banned because people disagree with them and may protest in response.

The government has used the character test to ban others entering Australia in recent years, including WikiLeaks whistleblower Chelsea Manning, Gavin McInnes, the leader of the far right Proud Boys group, and notorious English conspiracy theorist David Icke.

The initial decision to reject Mr Yiannopoulos' visa was met with a furious response from pro-free speech Coalition MPs, One Nation leader Pauline Hanson, and some media commentators including Sky News host Andrew Bolt.