The actress joins a host of other celebrities in supporting marriage equality in Australia.

Margot Robbie used her hosting slot on Saturday Night Live to show her support for marriage equality in her home country of Australia.

The Harley Quinn actress appeared on the show’s season premiere this weekend wearing a T-shirt that read “Say ‘I Do’ Down Under”.

The T-shirt also featured a map of Australia in rainbow colours and, though Robbie did not speak about the issue, her sentiment was clear.

Ahead of a showdown on the issue this month, a range of stars have backed the Say I Do Down Under campaign.

Heading the pack is Australian gay icon Kylie Minogue – who has been vocal in support online of the campaign, which just so happens to be headed by her fiancé Joshua Sasse.

Sasse wrote: “Have you ever been in love? Are you in love? Could you imagine yourself there one day?

“Imagine too then, having your government deny you that right — what if you couldn’t marry that person. Your person.

“I was shocked to find out earlier this year that same-sex marriage in Australia is still illegal.

“There are many hurdles to jump in order to make constitutional change, but we are now the closest we’ve ever been to that change.

“Let’s raise our voice and public support for change. Get a shirt. Wear your heart on your sleeve.

Support Australians 4 Equality, a coalition of organisations working to deliver a winning campaign so we can legalise all love in this country and SAY ‘I DO’ DOWN UNDER.”

Minogue also tweeted: “Please one and all retweet and spread the love!!! #sayidodownunder.”

Others to back the campaign include Dolly Parton, Jake Shears of the Scissor Sisters, and actress Kelly Ripa.

Equal marriage in Australia is at risk of being shot down, after Prime Minister Malcolm Turnbull failed to agree a compromise deal with opposition parties.