L'Heureux said that the follow-up will be based on an original script by Frank Miller, while the first film was adapted from his graphic novels, Mania reports.
He said: "As simple as Sin City seems, it's a very complex scheduling with all these actors and it's a very demanding shoot to be on a sound stage all day long. We have to space it for Frank.
"There's also talk, of course, of Sin City 3."
The producer added that Miller is currently working on the screenplay for Hard Boiled , which he is adapting from his 1990 comic book.
He added: "We're still developing it. We got the project in turnaround from Warner Bros and Frank. It's such a pleasure to work with someone like Frank Miller. He's so smart and passionate about story at all levels from 1940s noir pulp to modern film."
In April, Angelina Jolie reportedly resumed talks to join the cast of the Sin City sequel.