An argument has erupted in Melbourne between men wearing SS Nazi insignias, young men draped in Australian flags, placard-waving atheists and a Muslim couple.
The incident came as police in Melbourne and other cities around Australia came out in force on Sunday to ensure a repeat did not happen of the violent street battle between Muslim protesters and authorities in Sydney last weekend.
The argument in Melbourne was a rare incident, with authorities across Australia largely applauding the restraint shown after last week's violence.
The flash of anger erupted on the steps of Melbourne's State Library, where earlier in the week Muslim groups announced they would stage a rally.
The rally, however, was called off over fears it would not be peaceful.
This did not deter small non-Muslim groups, watched carefully by police, from gathering on Sunday.
The argument broke out after four atheists arrived at the library carrying placards, one of which declared, "(Like All Religions) Islam is false".
A Sydney Muslim couple was drawn into a debate with the atheists over the content of their signs.
Tensions escalated as men, some with SS insignias, and others draped in Australian flags who had been waiting at the library for several hours, got involved.
There was no physical violence, but the crowd of onlookers swelled to about 40 as tempers flared.
One man, who did not want to be named, said he was there because he was concerned by what he saw on television last week.
"It's an anti-thing," he told AAP.
Some men on the library steps were dressed in T-shirts promoting the Nationalist Alternative - a group devoted to reaffirming Australian culture and restoring the sovereignty and independence of the Australian nation, according to its website.
The men broke into a chorus of "Aussie Aussie Aussie" when a Muslim man who had become embroiled in the debate walked away.
They waved flags, cheered and made rude gestures with their hands, to the gathered crowd which was mostly media.
Meanwhile, police in NSW described the operation to avoid a repeat of last weekend's violent Sydney protests as a success.
An extra 300 officers were brought onto Sydney's streets and public transport networks following the riots sparked by a US anti-Islamic film posted on YouTube.
NSW Police Assistant Commissioner Alan Clarke praised Muslim community leaders, who condemned the violence, for helping make sure this weekend passed without event.
"We certainly saw this weekend as a milestone in returning to normality and we feel we've achieved that," he said.
A week ago there were angry scenes as demonstrators clashed with police in Sydney, leading to 11 arrests and 25 charges.
Officers will continue monitoring social media outlets following the arrest of two men for attempting to incite further protest activity.