Margot Robbie and Jared Leto as Joker and Harley Quinn in Suicide Squad. Picture: Suicide Squad/Instagram

Jared Leto and Margot Robbie are set to reprise their roles as The Joker and Harley Quinn in a "criminal love story" spin-off.

The two Hollywood stars first appeared as the iconic villains in the 2016 blockbuster 'Suicide Squad', and it has now been reported they are set to get their own movie which will detail the twisted relationship between two of Batman's most deadly foes.

Glenn Ficarra and John Requa, who wrote and helmed 2011's 'Crazy, Stupid, Love' - and also worked as directors and executive producers on NBC's hit drama 'This Is Us' - are reportedly in "final negotiations" to helm the as yet untitled movie.

According to The Hollywood Reporter magazine, the movie is being described as a "criminal love story," with one source adding: "[It is] an insane and twisted love story. 'When Harry Met Sally' on benzedrine."

News of the project comes as Warner Bros. are planning the sequel to 'Suicide Squad', which will also see Jared, 45, and Margot, 27, reprise their roles.

The Hollywood Reporter states that the studio plans to release 'Suicide Squad 2' - which was recently put on the fast track and is now searching for a director - first, and then the Joker/Harley spin off, but sources say both projects are moving quickly as the studio is conscious of actors holding their agreements.

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.