Appearing on the ABC's Q&A program on Monday night, Mr Turnbull, along with others on the five-person panel, responded to a question from audience member Osmond Chiu, one of the individuals who took offence to remarks by Senator Abetz during a Senate inquiry last month.

Mr Chiu, a research fellow with think tank Per Capita and a trade union employee, appeared before the Senate's Foreign Affairs, Defence and Trade References Committee in October. He said Senator Abetz, who is deputy chair of the committee, had asked him and two other Chinese-Australians to condemn the Chinese Communist Party, which Mr Chiu described as feeling like "a demeaning public loyalty test".

He asked the panel whether or not it believed that was acceptable behaviour from a senator.

"I don't think I've ever felt singled out on the basis of my cultural background in that way," Mr Chiu said.

After former New South Wales Labor premier and foreign minister Bob Carr said the senator had behaved like a "tinpot Joe McCarthy", Mr Turnbull, an enduring adversary of Senator Abetz, weighed into the matter.

"What was said to you is disgraceful," Mr Turnbull told Mr Chiu. "It was a surreal experience."

"Can I tell you, having known Eric Abetz for a long time, surreal is often the adjective you apply to encounters with him.

"He is right on the fringe of the Liberal Party. He's a sensationalist. He does not represent the attitudes or views of the Liberal Party at large.

"Eric Abetz absolutely should apologise to Osmond. But let me tell you, he never will."

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Today, the senator fired back at Mr Turnbull, saying his "commentary" on Monday night was "yet another unedifying spray in a very long list against former colleagues".

"He regrettably further diminishes himself each time he does so," he said. "Quite frankly, it's sad."

"Whilst prime minister, Mr Turnbull tried to force an unconscionable extradition treaty with the Chinese Communist Party dictatorship through our party room. I strongly opposed the measure which thankfully helped to derail it. In fact, I was the only one to stand up in the party room to oppose it.

"There is no doubt I was on the right side of history and in tune with the will of the Australian people and the Liberal Party membership.

"Not 'sensationalist'. Just sensible."

The conservative Senator Abetz was employment minister in former prime minister Tony Abbott's Cabinet before the latter was deposed in a leadership spill in 2015 and replaced by Mr Turnbull, who Mr Abbott had himself successfully toppled in a challenge for the Liberal leadership six years previously.

Senator Abetz was booted from the ministry when Mr Turnbull, a leading moderate in the party, embarked on a Cabinet reshuffle.

Meanwhile, the pair were together embroiled in the so-called Utegate affair in 2009, which saw Senator Abetz and Mr Turnbull, then opposition leader, try to expose prime minister Kevin Rudd as having supposedly given preferential treatment to a friend under Labor's OzCar assistance program for struggling car dealerships.

But the unlikely alliance was short-lived, with it being revealed the senator and the Liberal leader had unwittingly relied on a fake email as evidence for their claims, provided to them by Treasury official Godwin Grech.