James Gunn says the 'Guardians of the Galaxy' characters were initially only supposed to have ''cameo'' roles in 'Avengers: Infinity War'.

The 53-year-old director - who helmed the standalone 'Guardians' movies - revealed during a watch-party how the characters became increasingly prominent in the Marvel film as it evolved.

Asked whether he knew the role the characters would play in 'Avengers: Infinity War' and 'Avengers: Endgame', James replied on Twitter: ''Originally they were solely going to cameo in ''Avengers 3'' but by the time I was writing the screenplay for Vol 2 it became something more. #QuarantineWatchParty #GotGVol2 (sic)''

'Infinity War' was helmed by Joe and Anthony Russo, with the movie boasting a star-studded cast that included the likes of Robert Downey, Jr, Tom Holland, Chris Hemsworth and Scarlett Johansson.

James plans to ''wrap up'' the stories started in 2014's 'Guardians of the Galaxy' with the next instalment of the franchise.

The filmmaker previously teased what fans can expect from the movie in an Instagram post.

Responding to fan questions on the photo-sharing platform, James - who directed the original 'Guardians of the Galaxy' and 'Guardians of the Galaxy 2' - shared: ''If everything goes to plan it will wrap up the stories I started in Guardians 1. (sic)''

There had previously been doubts as to whether the third 'Guardians' film would even be made, after Disney fired James following the emergence of a series of offensive tweets.

The company subsequently rehired the filmmaker, who took ''full responsibility'' for the controversy.

The director previously said: ''I feel bad for that and take full responsibility.

''Disney totally had the right to fire me. This wasn't a free speech issue. I said something they didn't like and they completely had the right to fire me. There was never any argument of that. That first day ... I'm going to say it was the most intense of my entire life.

''There have been other difficult days in my life, from the time I got sober when I was younger, to the death of friends who committed suicide.

''But this was incredibly intense. It happened, and suddenly it seemed like everything was gone. I just knew, in a moment that happened incredibly quickly, I had been fired. It felt as if my career was over. (sic)''