The sheer number of "disturbing" responses in support of the Christchurch terror attack shows how hard it is to identify potential far-right terrorists, Prime Minister Scott Morrison says.
Mr Morrison says supporters of Australian Brenton Tarrant, who is facing trial over the shooting which left 50 dead in two Christchurch mosques, should be called out.
Tarrant, from Grafton in NSW, has been charged with murder over the terrorist attack that also left another 50 injured.
The 28-year-old was not on any watchlist in Australia or New Zealand, despite online profiles linked to him containing white supremacist material.
"I know there's been a number of comments made about how the terrorist was able to go for so long undetected," Mr Morrison told an Australia Israel Chamber of Commerce lunch on Monday.
"I would encourage people who maybe think this is an easy thing to identify, just go on social media, read some of the comments that have been made in relation to the stands that I or others have taken in renouncing these attacks, and see some of the comments that are up there.
"There's hundreds of them, if not thousands. This is what I've found truly disturbing, in addition to the sheer atrocity."
Mr Morrison is meeting with security bosses on Monday to discuss the threat of white supremacists and far right terrorism in Australia and New Zealand.
"Sadly, white supremacy and separatism in Australia is not new. It's been around for well over a century," he said.
"At one time in Australia's history it could even be argued it held some sort of mainstream position. Thankfully that's no longer the case."
New Zealand could deport Tarrant after he faces trial and Australian Foreign Minister Marise Payne confirmed he could come home.
"We would have those discussions with New Zealand if and when the time comes," Senator Payne told Sky News.
Opposition Leader Bill Shorten said police need to track hate crimes like the United States does.
"This country needs to be better at recording hate crime ... you can't beat what you can't measure," he told reporters in Perth.
Home Affairs Minister Peter Dutton said Australia's terror alert system remains under review.
"In these circumstances, people are always worried about a retaliatory attack or a copycat of what we saw, the atrocity that we saw in Christchurch," Mr Dutton told ABC radio.
Greens senator Mehreen Faruqi said Mr Dutton and other Liberal politicians had whipped up anti-Muslim sentiment, giving a "nod and a wink" to white supremacists.
"What they've been doing does come with a cost, it does come with consequences because really they've been playing games with our lives," she said.
Mr Dutton said Senator Faruqi was "just as bad" as independent Fraser Anning, who blamed Muslim immigration for the attack, but Finance Minister Mathias Cormann disagreed.
"The comments by Fraser Anning over the weekend were uniquely inappropriate," Senator Cormann told the ABC.
