A previously unreleased version of 2017 superhero movie "Justice League" by director Zack Snyder will debut on the HBO Max streaming service in 2021, executives said on Wednesday, in response to a years-long campaign by fans.

Snyder oversaw filming of "Justice League," which brought together DC Comics heroes Batman, Superman, Wonder Woman, Aquaman and others. The director had put together a cut of the movie before he stepped aside to deal with a family tragedy.

"Avengers" director Joss Whedon took over in post-production to oversee reshoots and complete editing. The final product drew lackluster reviews. Just 40 percent of the reviews on the Rotten Tomatoes website gave "Justice League" a positive rating.

Fans have speculated that they would like Snyder's version better. #ReleaseTheSnyderCut became a trending hashtag starting in 2017 and remained popular worldwide. Supporters even bought a billboard in New York's Times Square in October 2019 to promote their cause.

"The fans have asked, and we are thrilled to finally deliver," said Robert Greenblatt, chairman of AT&T Inc's Warner Media Entertainment and Direct-To-Consumer division, which will launch HBO Max on May 27. HBO Max will compete with Netflix Inc, Walt Disney Co's Disney+ and other subscription video services vying for online audiences.

"Justice League" stars Ben Affleck as Batman, Henry Cavill as Superman, and Gal Gadot as Wonder Woman.

(Cover image: Actor Ben Affleck poses amid the world premiere of Warner Bros. Pictures' "Justice League" in Los Angeles, California, U.S., 2017. /Reuters