An Australian senator, who resigned from the opposition’s frontbench after he said that allowing same-sex couples to marry could lead to sanctioning polygamy and even bestiality, says his original comments were correct.

Cory Bernardi made the comments shortly before Australia’s Parliament overwhelmingly voted against a marriage equality bill in September 2012.

The Liberal Party senator queried the next step if same-sex marriage was legalised.

“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 at the time.

“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?”

Speaking to The Age on Monday, Mr Bernardi said: “If we go back to what I suggested in the Parliament when the same-sex marriage debate came up, there is actually now a petition being put together for the Parliament by green activists to recognise multi-member unions,” he said.

“Now I said that would happen. It’s happening. We haven’t even taken the first step.”

“I think there should be alarm. If you’re going to redefine a word to satisfy demands of a minority then you are going to face continuing demands in that space.”

The petition he refers to, from the Polyaction Amory Lobby, reportedly has about 25 signatures.

Mr Bernardi admitted linking same-sex marriage to bestiality was extreme but said the Greens agenda endorsed the “abhorrent and disgusting” act.

“Whether people agree with it or want to interpret it incorrectly, what I said was correct. It may have offended some people and it wasn’t intended to offend people but people drew inferences from it that they should never have done,” he said.

Australia’s Green Party has described Mr Bernardi’s remarks as “disgusting”.

Mr Bernardi also attacked Australia’s former Prime Minister Kevin Rudd for changing his position on equal marriage, saying he was a “conviction politician of convenience” who used to deliver doorstep interviews outside a church.

The current Prime Minister, Julia Gillard, remains opposed to equal marriage.

In April, Australia’s Liberal Party leader, Tony Abbott, said he opposed proposals to hold a public vote on equal marriage during September’s federal election.