TONY Abbott’s sister has denied the same-sex marriage debate has split the Abbott family despite an ugly spat between the siblings over her first marriage.

Sydney Councillor and marriage equality advocate Christine Forster yesterday accused her brother of scoring a cheap political point when he used a radio interview to reveal that she had privately “joked years ago that she’d just got herself out of one marriage — why would she be rushing into another one?”.

Cr Forster, who is now in a same-sex relationship and is campaigning in support of a ‘Yes’ vote, hit back, saying Mr Abbott’s comments were “hurtful” and the breakdown of her first marriage was not something to laugh about.

In an interview on the Nine Network on Friday morning, she denied the family was split, but admitted the period leading up to the postal plebiscite would be “very difficult”, and her brother wasn’t making it any easier.

Mr Abbott has begun a personal campaign to push the “No” vote, equating same-sex marriage with political correctness. Ms Forster said her brother’s comments hurt gay people.

“To say this is an issue about political correctness does trivialise something that is a very deeply held belief by myself and many other members of the community,” she said.

“This is not about political correctness. This is about basic rights before the law. It’s about fairness. It’s about equality. It’s about respect. It’s about inclusion.

“It is nothing to do with political correctness. It’s something that I think most Australians think, should have happened some time ago, and they expect that will happen in the wash up from this vote.”

But when asked if her brother’s anti-gay interventions had affected the family, she said the pair had agreed to disagree.

“The Abbott family is like every other family. We do have differences of opinion on some things but we are a normal, functional family,” she said.

“The fact that Tony and I have agreed to disagree on this question in particular doesn’t impact the fact that we’re brother and sister. We love each other. In all other respects we try to get along.”

Mr Abbott yesterday came under fire for relaying the private conversation he had with his sister some years ago, in which he claims she said she did not support gay marriage.

City of Sydney Councillor Christine Forster tells us how she feels about her brother Tony Abbott's comments on same-sex marriage. #9Today pic.twitter.com/9H93MWy2Rj — The Today Show (@TheTodayShow) August 10, 2017

Cr Forster quickly fired back, saying her divorce had been “a really traumatic time in my life.”

“Anyone who’s been through a marriage breakdown will know that’s a terrible traumatic process, certainly not something that I joke about, then or now. It was a terrible thing for everyone involved. My ex-husband, my children, other family members . it was awful,” she told 2GB.

“You know, it’s hurtful to hear those private conversations being aired in public for the purposes of scoring a political point, and I wish he hadn’t done that.”

Mr Abbott is urging people to vote “no” in the postal vote to “stop political correctness in its tracks.

“If you’re worried about religious freedom and freedom of speech, vote ‘No’, and if you don’t like political correctness, vote ‘No’ because voting ‘No’ will help to stop political correctness in its tracks,” he said.

Cr Forster responded on Twitter by urging Australians to vote ‘Yes’ if they valued mutual respect.

“If you want all Australians to be equal: vote yes. If you believe in free speech: vote yes,” she wrote.

Ms Forster, who has been engaged to her partner Virginia Edwards since 2013, also said: “If you want the person you love to be in every sense a part of your family: vote yes.”