Actor Margot Robbie arrives for the screening of "I, Tonya" during the Toronto International Film Festival in Toronto on Friday, Sept. 8, 2017. Picture: AP

Margot Robbie has hinted the upcoming Joker and Harley Quinn spin-off movie will focus more on the pair's unhealthy romance.

The 27-year-old actress starred as the female villain in the DC Extended Universe (DCEU) ensemble movie 'Suicide Squad' alongside Jared Leto's evil Joker, and has said said she's excited for the pair to reunite in the planned spin-off feature as she's a "sucker" for their "messed up" love story.

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She said: "I'm personally a sucker for a love story. In any iteration. I think people enjoy seeing two characters who, in Harley and Joker's case, would die for one another. It's kind of romantic in a messed up way."

Margot also praised the project's directors Glenn Ficarra and John Requa - whom she previously worked with on 'Focus' and 'Whiskey Tango Foxtrot' - as "brilliant".

Speaking to ComingSoon.net, she added: "They're great! It's fun working with a directing duo, and I love them. I've obviously done two films with them so I think they're just brilliant."

The spin-off movie is believed to be a "criminal love story," with one source adding: "[It is] an insane and twisted love story. 'When Harry Met Sally' on benzedrine."

Meanwhile, it was previously reported that Martin Scorsese was set to helm a separate story centred around The Joker, which would not feature Jared in the role.

Warner Bros. and DC were believed to be in the early stages of putting the 'Batman' spin-off together, and it will be the first movie under a new banner which is yet to have been given a name.

While plot details are yet to be revealed, it is thought the movie could focus around The Joker's origin story and be different to any other iteration.