A making-of documentary about Zack Snyder’s Justice League is set to air after the film’s premiere.

Cameraman Simon Firsht revealed on social media, in a since-deleted Instagram post (per ComicBook), that a 30-minute doc will debut at the same time as the four-hour film, including “never before seen footage”.

• READ MORE: ‘Zack Snyder’s Justice League’ review: an unflinching update fans can be proud of

“The week has finally arrived for the Zack Snyder cut!!” Firsht wrote on Instagram.

“It’s being released worldwide on Thursday March 18th along with a 30min documentary about the making of JL, which includes all my original ‘never before seen’ footage from the set and a major interview with Mr Snyder himself.

He continued: “I’m sooooo happy it’s finally going to be seen by all the fans that have made this unprecedented event happen!! I also have the honor of lighting and filming the virtual premiere live this Wednesday 17th.”

Warner Bros, HBO Max and Zack Snyder have not yet confirmed Firsht’s announcement or added any more detail on the making-of film.

In a four-star review of Zack Snyder’s Justice League, NME wrote: “Zack Snyder’s Justice League does justice by the comic publisher’s raft of pioneering creations. And it’s justice for a DC comics fanbase that has been put through the ringer with poor adaptations and meandering visions for much of the last decade.

“Because there’s one more thing that needs to be said – Zack Snyder’s Justice League is really very good.”

The film will premiere on HBO Max worldwide tomorrow, March 18.