'Avengers: Infinity War' director Anthony Russo says the new Marvel movie will mark something unprecedented in the history of the franchise.

The 44-year-old movie-maker - who is helming the much-anticipated new film alongside his brother Joe - has claimed that the task of bringing together so many popular superheros for one movie is something that's never been seen before.

He explained: ''There are a lot of characters in this movie that have tones that they're bringing from their own franchises.

''I think it's a very unique film, I don't think there are a lot of movies that have the kind of tone that this movie has, because it's a combination of franchises and I don't think we've ever seen that before on this scale.

''So I think it's got a really unique tone to it, and I think it's impulsive, I would say it's an adventure film, but it has elements of ... we were inspired by 90s crime films when we were working on the script. So it's got an energy to it, a bit of a smash and grab energy.''

The film features a star-studded cast that includes the likes of Robert Downey Jr, Tom Hiddleston, Chris Evans, Chris Pratt, Benedict Cumberbatch, Vin Diesel and Scarlett Johansson.

'Infinity War' sees the Avengers join forces with the Guardians of the Galaxy to stop Thanos, and Anthony has teased their role in the movie.

He told Collider: ''Everyone is interwoven in this plot in a way where they have an emotional connection to the story, and are emotionally affected by the stakes of the movie.

''You can't tell a movie with this many characters and not have each of those characters show up and honour them from the different franchises if they are not motivated to be there, if they are not in life or death circumstances, if they are not fighting to save their belief system or their way of life.''