Former cabinet minister Eric Abetz has used the offensive word “negro” while he was speaking about opposing views on same-sex marriage during a live radio interview on Thursday.

Mr Abetz was speaking to 2UE’s Justin Smith when he dropped the outdated and offensive slang word.

The Senator uttered the word when rejecting a suggestion by Mr Smith that refusing to bake a cake for a same-sex wedding was on par to discriminating against Asian people.

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“Those sort of analogies are quite offensive and that sort of analogy was completely debunked by Justice Clarence Thomas, the negro American on the Supreme Court of the United States dealing with this issue … who dissented on the issue of marriage as well,” Mr Abetz said on air.

Radio host Mr Smith tried to interject, questioning why he used the word.

But Mr Abetz kept speaking, saying: “Trying to bring race into it has now been completely dropped.”

The pair had been speaking about the right of pastry chefs to refuse to make wedding cakes for same-sex couples who intended to marry.

Mr Abetz said business people had the right to decide for themselves, and if a baker refused to produce a cake for a Liberal Party function, “I don’t think I should be able to sue them or put them out of business”.

Mr Smith said Mr Abetz would be angry and would complain to the Senate about “the cake that got knocked back”, Fairfax Media reported.

Mr Smith then said the refusal was akin to saying: “No Asians please, I don’t like Asians so don’t come in here and buy a cake.”

Then Mr Abetz hit back.