Attorney-General George Brandis has accused Labor’s Penny Wong of attacking former human rights commissioner Tim Wilson on the basis of his same-sex relationship with a Liberal Party member.

Mr Wilson, now the Liberal MP for Goldstein, last year attended a $40-a-head cocktail function in Melbourne’s Essendon billed as “An Evening with Tim Wilson” the proceeds of which went to the Liberal Party.

Senator Wong today challenged Senator Brandis to reconcile that evidence with the Attorney-General’s previous assurance that Mr Wilson had not attended Liberal fundraisers in his capacity as a commissioner.

Mr Brandis answered that Mr Wilson had attended Liberal Party functions as the partner of his fiance, Ryan Bolger, a Liberal Party member.

“I don’t say it lightly but, in view of the evidence before this committee, what Senator Wong has done has been to attack Mr Wilson because of his relationship status and that is a disgraceful thing to do,” Senator Brandis told an estimates hearing in Canberra.

“Your attack on Mr Wilson because of his relationship status is a disgrace. That is absolutely a disgrace.”

Senator Wong was incensed at the allegation, saying it was “quite clear” from a promotional flyer that Mr Wilson was not merely a guest of Mr Bolger but the headline attraction for the fundraiser.

“It’s all very well for you to bluster. I’ve been accused of attacking someone on the basis of their partner. That is not the case. The minister is seeking to avoid answering the question,” the senator said.

“That is demonstrably untrue and beneath contempt that he would say that.”

“It is quite clear. This not Mr Wilson attending as a guest of his partner; this is Mr Wilson headlining a fundraiser.”

Senator Brandis said there was “nothing at all” in the flyer to suggest Mr Wilson was aware it was a fundraiser.

The function flyer read: “The Essendon SEC (State Electoral Conference) in conjunction with Essendon West Branch and Moonee Ponds Branch would like to invite you to an intimate cocktail function with Tim Wilson, Australia’s Human Rights Commissioner. Here about his thoughts on his role and the future of Rights in Australia … Cheques: Payable to ‘Liberal Party of Australia, Victorian Division, Essendon SEC’”

Labor senator Murray Watt noted: “It doesn’t say ‘An Evening with Tim Wilson’s Fiance’.”

Mr Wilson resigned from the Liberal Party before taking up the role of human rights commissioner.

Upon accepting the role Mr Wilson advised the Labor, Liberal and Greens party secretaries that he would be available to address their meetings about the Human Rights Commission and his role in particular. However, he said, he would not attend party fundraisers in that capacity.

Senator Brandis subsequently told the committee the event was “not a fundraising function”.

“The cost that was advertised, $40 per person, was to cover the cost of function with no margin for profit at all,” he said. “It was a Liberal Party event, but not a fundraising function.”