Relations have soured between Stallone and Willis since the pair, with fellow action star Arnold Schwarzenegger, launched the Planet Hollywood restaurant chain in 1991.
In leaving The Expendables, Willis is walking away from a franchise that has taken a combined US$574 million ($721 million) at the global box office. Willis, who blamed a grouchy recent appearance on the BBC's The One Show on jet lag, may not have forgiven Stallone after it became apparent that he was only the third choice for the role of Mr Church, who hires the film's eponymous band of muscle-bound mercenaries, led by Stallone's Barney Ross, to carry out missions.
Schwarzenegger was initially offered the role of Mr Church but upgraded instead to the fellow mercenary leader Trench. Kurt Russell then turned it down before Stallone, seeking a big action name, remembered his old pal Willis, who accepted after being granted a scene alongside both Stallone and Schwarzenegger.
It is not known whether Ford will take over the role of Mr Church or be given a new character. At 71, Ford remains as busy as ever and is also due to star in the forthcoming films Anchorman: The Legend Continues, Star Wars: Episode VII and Indiana Jones 5.
Production on The Expendables 3 is set to begin this month for a 2014 release. The film is expected to feature Jackie Chan, Wesley Snipes and Nicolas Cage, with Mel Gibson also tipped for a role. The series has featured Mickey Rourke and Dolph Lundgren.
- Independent