Prime Minister Malcolm Turnbull has defended his marriage equality credentials after a radio presenter took him to task over extreme anti-gay posters that were plastered across Australian cities this week.

In an interview with Sydney’s 2Day FM radio on Tuesday, host Em Rusciano told Mr Turnbull that the “respectful debate” that he had championed was “with all due respect … in the toilet”.

Rusciano noted the emergence of anti-gay posters bearing the message ‘Stop the Fags’ and containing widely discredited statistics about the LGBTI community.

“This plebiscite that you’re allowing has emboldened people who are anti-homosexual to come forward in the light and say some pretty awful things,” she said.

“I am a mum and if my child was homosexual and hearing this rhetoric that is now openly available because of your government … What do you say to these kids and these parents?”

Listen to the interview below

The Prime Minister said he found the posters “hurtful” but argued that it was not right to shut down the debate.

“Well, Em, we’re in a democracy, right?” he said.

“What I would say to you, Em, is if you have friends who are really distressed by this sort of language, stand up for them. Put your arms around them.”

Asked what he would say to LGBTI Australians who “are feeling ostracised”, Mr Turnbull said: “Believe in yourself, believe in yourself. Be proud, be proud of yourself.”

But Rusciano put it to the Prime Minister that equality was not up for debate.

“Is (the debate) legitimate though? Prime Minister, I don’t believe you believe it’s legitimate. I don’t believe in your heart you do,” she said.

The extreme campaign posters are said to be the work of neo-Nazis. Photo: Twitter

The PM said that Rusciano was hurting the ‘Yes’ case with her comments, arguing that the vast majority of people opposed to same-sex marriage were not homophobic.

“Em, look, can I, let me give a tip. What you’re saying there is undermining the case for marriage equality,” he said.

“A key thing is, you cannot ask for respect from the ‘no’ case, from the ‘no’ case, if you’re not prepared to give respect to the ‘no’ case.”

When the PM announced the postal plebiscite last month, he confirmed he would not be actively campaigning for the ‘Yes’ case.

But on Tuesday, he argued the case forcefully, a cause he said he and his wife Lucy had long supported.

“I do not think that if a gay couple gets married, who are living together, gets married, that doesn’t threaten my marriage to Lucy, which is nearly 38 years of marriage,” he said.

“And I’ll tell you, the threats to marriage are not gay people getting married. The threats are desertion, cruelty, neglect, abandonment, indifference. Those are the threats.”

Mr Turnbull’s comments come as former prime minister Tony Abbott steps up his case against same-sex marriage.

Having argued a voting no would help stop ‘political correctness’, on Monday he told 2GB: “The best way for standing up for traditional values, (if you), don’t like the direction our country is headed in right now, is to get that ballot paper out and vote no.”

Ballots for the postal ballot will be mailed out later this month and will be due back on November 7.

The survey, conducted by the Australian Bureau of Statistics, will not be covered by the same rules that govern an election campaign.

Opposition Leader Bill Shorten has previously said he would hold the PM responsible for any hate speech that was unleashed during the campaign.