A fourth 'Expendables' movie is in the works.

Sylvester Stallone, Jason Statham, Dolph Lundgren and Randy Couture are all set to reprise their roles from the previous three films.

The quartet will be joined in the new movie by Megan Fox, 50 Cent and Tony Jaa, with stuntman-turned-director Scott Waugh helming the project.

Lionsgate and Millennium Media have agreed to revive the action franchise and the plot is expected to once again focus on a group of veteran mercenaries. Insiders have said that Jason's character will have the main part in the film, with Megan portraying the female lead.

Spenser Cohen has written the script with revisions by Max Adams and John Joseph Connolly.

Jason is producing the flick with Kevin King Templeton and Millennium's Les Weldon, Yariv Lerner, Jeffrey Greenstein and Jonathan Yunger.

Jason Constantine, president of acquisitions and co-productions for the Lionsgate Motion Picture Group, said: "It's so much fun to bring these stars together for a no-holds-barred action film.

"The new film will raise the stakes and be the biggest, most badass adventure yet."

Millennium president Jeffrey Greenstein suggested that "popcorn entertainment is guaranteed" and promised that the new members of the cast will "keep it fresh and fun".

The original movie was directed by Stallone, who also wrote the script with David Callahan, and assembled some of the biggest names in the action genre from the 1980s – such as Bruce Willis and Arnold Schwarzenegger – and paired them with wrestlers, martial artists and younger action stars.

The franchise proved successful and sequels followed in both 2012 and 2014, although the latest movie had been stuck in development for several years with changing writers and directors.