Ezra Miller is working on a ''darker'' script for 'The Flash' movie.

The 26-year-old actor - who has already portrayed the comic book character in 'Batman v Superman: Dawn of Justice' and 'Justice League' - has reportedly disagreed with writer-director duo John Francis Daley and Jonathan Goldstein on the story and has started working with comics author Grant Morrison on his own script.

According to The Hollywood Reporter, Ezra wants a ''darker'' take on the story, while Daley and Goldstein are keen for a lighter comic-book adaptation.

The script could be submitted by next week, while Ezra's holding deal with Warner Bros expires in May.

Meanwhile, Ezra recently insisted the delay on 'The Flash' is because they want to make sure the film is ''just right'' for the fans.

Filming was pushed back on DC's long-in-development standalone movie centred on the titular speedster until later this year, and Miller claimed the reason they are taking so long is because they want to create a whole new ''speedster multiverse'' beyond DC.

He said: ''We're talking about sparking a whole new universe, it's not just the DC multiverse, it's the speedster multiverse. And the speedsters are the ones who connect all the disparate pieces of it. 'Cause Marvel is a universe, right? It's a world with all the same characters in it. DC is a multiverse - all these different stories with different realities, different characters and different versions of characters. And the speedsters are the ones who move through it all.''

The 'Fantastic Beasts: The Crimes of Grindelwald' star added that they don't want to make the movie if it becomes anything but a ''consummate beautiful offering'' to fans.

He said: ''We're a little late, but the reason why we're late - and this is the honest to God truth - the reason why we're late is because we're all -- and I include myself in this -- we are very meticulously focused on making a movie that's not just one of the greatest superhero movies that we can possibly make, this movie is also going to be a gift to the fans.

''This movie's going to be a real pure offering to the fans of this material.

''And we've hit a couple of points in the script's development where we've looked at it and gone 'This isn't it, this isn't it yet.' ... I'm really delighted at how focused everyone is on getting it just right, and I'm really devoted to that as well.

''We won't make the film unless it's going to be this consummate beautiful offering to the fans, and to everybody.''

The movie is currently expected to be delayed until 2021.