The X-Men: Days of Future Past filmmakers have confirmed the plot of the 20th Century Fox sequel, Digital Spy reported.

Director Bryan Singer and writer-producer Simon Kinberg have explained the similarities and differences between the original, classic comic story and the film.

A featurette has also arrived in which Singer talks about his excitement at uniting the First Class cast with the actors from his X-Men films.

Days of Future Past will see Wolverine (Hugh Jackman) sent back into his past body to prevent an assassination that leads to a dark future for mutantkind. In the comic, the role was taken on by Kitty Pryde, portrayed by Ellen Page in the film.

Entertainment Weekly revealed that it will be Bolivar Trask (Peter Dinklage) - the inventor of the mutant-hunting Sentinel robots - rather than Senator Robert Kelly who is the target of the assassination attempt by Mystique (Jennifer Lawrence) and Magneto (Michael Fassbender).

Wolverine's mission also involves redeeming Magneto, Mystique and Charles Xavier (James McAvoy). "A lot of people have an emotional investment in [Mystique] not going to the dark side," said Kinberg.

Magneto is at that point imprisoned for the supposed assassination of JFK, while Xavier is a "drugged reclusive" living with Beast (Nicholas Hoult).

"The hope is that Days of Future Past will broaden the audience for X-Men such that it will motivate potential spinoffs even more," said Kinberg.

"Everyone grew up knowing Captain America or the Hulk, but not X-Men characters - I didn't even know who Wolverine was," added Singer. "I call X-Men the bastard stepchild of the comic universes."

The director has been accused of underestimating the huge popularity of the 1990s X-Men cartoon and his own films, which have left younger generations well versed in X-Men lore.

Sir Ian McKellen, Sir Patrick Stewart, Halle Berry, Shawn Ashmore, Omar Sy, Fan Bingbing, Adan Canto, Josh Helman and Evan Peters will also star in the film.

X-Men: Days of Future Past will arrive in UK cinemas on May 22 and in the US on May 23.