(CNN) Australia has long considered itself an immigrant nation. Every year, the number of Australians born overseas increases -- in 2017, it was more than one in four residents, or roughly six million people.

"Australia is the most successful multiculturalism society in the world, it's one of our greatest achievements," Australian Prime Minister Malcolm Turnbull told the national broadcaster in July.

But following an uproar over a neo-Nazi being interviewed on national television and repeated comments by top politicians over "African gangs," questions are emerging over whether Australia is a more racist country than it would like to believe.

"For the most part we are a highly cohesive and harmonious society but that doesn't deny for a moment that racism continues to be a significant social problem," Australia's outgoing Race Discrimination Commissioner Tim Soutphommasane told CNN.

On Sunday, nationwide broadcaster, Sky, aired an interview with far-right agitator Blair Cottrell, who has previously been accused in local media of calling for a portrait of Adolf Hitler to be hung "in every (Australian) classroom and every school."

The interview was pulled from social media and the network apologized after a large backlash, but the fact it was aired in the first place has raised questions about Australia's attitude to race.

In a speech to the Whitlam Institute in Sydney on Monday, after the interview aired, Soutphommasane said Australia's "racial harmony" was under threat.

"I take no pleasure in saying this, but, right now, it feels like there has never been a more exciting time to be a dog-whistling politician or race-baiting commentator in Australia," the outgoing commissioner told the audience.

Thanks to @Whitlam_Inst for hosting last night's speech & to all who came. Special thanks to @markdreyfusQCMP & Prof John Hewson for joining me in a discussion about the return of race politics. Here's the speech https://t.co/SMmMqBH0Dv pic.twitter.com/9KRtvQx1uc — Tim Soutphommasane (@timsout) August 6, 2018

Australians: Immigration levels 'too high'

Australia's population is expected to hit a record high of 25 million within days, according to the country's Bureau of Statistics, partially due to an influx of migrants, among them more than 500,000 Australian residents who were born in China.

But this diversity has often come hand-in-hand with discrimination against immigrants, from the infamous White Australia policy in the mid-20th century that effectively banned non-European migrants from settling in Australia, to the One Nation political party formed in 1997 to oppose Asian migration.

Polling by Australian research company Essential shows opinions on immigration are divided -- more than half of Australians considered multiculturalism to have "enriched the social and economic lives of all Australians," in a survey published in April 2018.

But in the same poll, 64% of those surveyed said they thought immigration levels to Australia over the past 10 years were "too high."

"Australia does multiculturalism far better than a lot of comparative countries. But I think Australia's problem, and our potential danger, is our complacency," Asian-Australian writer Benjamin Law told CNN.

Law said the majority of non-anglo Australians had experienced racism in their lifetimes, something the rest of the population might not appreciate.

"I think we are so enamored with the idea of ourselves as successfully multicultural and not racist that when actual racism is presented to us in our media, in our government, we don't recognize it," he said.

Since his term in office began in 2013, Soutphommasane has staunchly opposed a push by conservative politicians, media and commentators to change Australia's Racial Discrimination Act.

Efforts to reform the act have been a signature policy of Australia's conservatives in recent years. The Turnbull government attempted in 2017 to pass a bill which would have made it no longer illegal to "offend, insult or humiliate" people based on their race.

"People do have a right to be bigots, you know," then-Attorney General George Brandis said during a parliamentary debate on the issue in 2014.

African gangs

Not all the recent rhetoric has been focused at a legislative level, however.

In the past eight months, with a state election looming, conservative politicians and media figures have repeatedly claimed gangs of African youths are terrorizing the city of Melbourne.

Statistics from the Crime Statistics Agency do reveal Sudanese residents are over-represented in crime numbers in the state of Victoria, of which Melbourne is the capital.

Lending credence to this, Prime Minister Turnbull said there was a "real concern about Sudanese gangs," during an interview on Melbourne radio station, 3AW, in July.

However, crimes involving Sudanese residents account for just 1% of Victoria's total criminal activity , with the vast majority of crimes committed by Australian-born residents.

"If you were to focus on race and ethnicity only when talking about crime you end up with a distorted and dangerous debate," Soutphommasane told CNN.

Amid the debate around African gangs, Home Affairs Minister Dutton has been leading a campaign to look at potentially allowing special visas for white South African farmers to move to Australia.

In an interview on March 14, the Australian minister said he was concerned by reports of an alleged widespread campaign of violence against the white farmers.

"I've asked my department to look at options and ways in which we can provide some assistance ... I do think on the information I've seen people do need help and they need help from a civilized country," Dutton told Australian newspaper the Daily Telegraph.

'Boundless plains to share'

The less popular second verse of the Australian national anthem contains the lines, "For those who've come across the seas, we've boundless plains to share."

JUST WATCHED Racism speech shakes up Australia Replay More Videos ... MUST WATCH Racism speech shakes up Australia 02:43

While Soutphommasane said Australia still has an enormous, cohesive multicultural society, he is concerned there was a "very real prospect" of racism becoming normalized in Australian public debate.

"I do take confidence from the enormous support that exists in Australian society for multiculturalism. The majority of Australians believe (it) makes Australia better country," he said.

Law said racism in Australia appears to come in waves, and growing up as a young Asian-Australian in the 1980s it was something he rarely encountered.

But he said he was concerned about what effect the latest round of rhetoric was having on young Australians, from migrant families, growing up in Australia today.

"I am kind of worried about how laissez-faire we've become with tolerating hate speech in this country," he said.