Australian Senator Cory Bernardi has called on former Liberal leader and current Communications Minister Malcolm Turnbull to stop publicly advocating equal marriage or resign from government.

At the weekend, Mr Turnbull said the Coalition should allow a conscience vote on same-sex marriage, which he would “certainly” vote for.

Mr Turnbull is at odds with Australian Prime Minister and Liberal Party leader Tony Abbott who remains opposed to equal marriage.

Last week, Mr Abbott defended his decision to challenge the Australian Capital Territory’s same-sex marriage law, resulting in 27 couples having their marriages declared invalid after the High Court unanimously ruled that the ACT’s laws were unconstitutional.

Mr Abbott is facing calls from senior members of his Liberal Party to allow MPs in the Australian Federal Parliament a free vote on legalising same-sex marriage.

Communications Minister Malcolm Turnbull said it was significant that the High Court ruled same-sex marriages were contained within the context of marriage in the Constitution, but it was up to the Federal Government to legislate on the matter.

“I think there is a reasonable prospect of a change to the law in this parliament,” Mr Turnbull told ABC radio on Friday.

“If Malcolm Turnbull wants to talk about fringe issues outside party policy, he should resign from the frontbench,” Mr Bernardi said in response.

“Our longstanding party position is that marriage is between a man and a woman.

“Our frontbenchers need to reflect that in any comments they make.

“When you are a frontbencher there is no room for a personal view.”

Mr Bernardi resigned from the Liberal Party’s frontbench in September 2012 after he said that allowing same-sex couples to marry could lead to sanctioning polygamy and even bestiality.

“Is having three people that love each other should [they] be able to enter into a permanent union endorsed by society, or four people?” he said in Parliament.

“There are even some creepy people out there, who say that it’s ok to have consensual sexual relations between humans and animals. Will that be a future step?”