Steven DeKnight hopes Charlie Hunnam will come back for a third instalment of the 'Pacific Rim' franchise.

The 37-year-old actor starred as hero Raleigh Beckett in Guillermo Del Toro's first instalment of the sci-fi franchise, but due to scheduling conflicts, he was unable to reprise his role in DeKnight's sequel, but the filmmaker hopes Hunnam will return in the future.

In an interview with Collider, DeKnight said: ''There was a version that was shot where what happened to him [Raleigh] was explained and talked about.

''We tested it, but people had more questions. We decided we didn't want to lock ourselves in and say Raleigh is dead or Raleigh has retired, which seemed a little cheap.

''We wanted to leave it open for the third instalment of the movie in case we can get Charlie Hunnam back.

''The only reason Charlie isn't in the movie is scheduling problems, he had his dream project, a remake of 'Papillon', that as we had finished the script with him in it, it was announced he was doing 'Papillon', his passion project and unfortunately the dates were exactly the same as ours, right in the middle of when we would shoot

''So very sadly he couldn't be a part of this one, but hopefully in a future instalment he will be.''

The first film followed mankind's attempts to stop monstrous creatures known as Kaiju - who entered from breaches in the Pacific Rim - from destroying the planet.

Humans created giant robots called Jaegers - designed to be piloted by two humans locked together in a neural bridge.

However, humanity's hopes relied on a washed-up ex-pilot Raleigh Becket (Hunnam) and Stacker Pentecost (Idris Elba).

The new film 'Pacific Rim Uprising' - which is set 10 years after the original - follows Jake Pentecost (John Boyega), the son of hero Stacker who sacrificed himself to save the world, who rises up to stand against the evolved alien race Kaiju alongside a rogue Jaeger to prevent humanity's extinction.

Scott Eastwood - who stars in the sequel - also revealed that Hunnam - who was set to reprise his role in the sequel but due to scheduling difficulties was unable to - is up for returning as well for a third movie.

The Hollywood hunk said: ''Absolutely! Charlie Hunnam and I sat down and talked about this movie.

''We actually wrote an entire script with Raleigh Becket as the main character. I turned it in.

''Everybody loved it and the next day it was announced that he was doing the remake of 'Papillon', which shot at the exact same time we were, and I know it was a passion project for Charlie.

''I love Charlie. I would love to work with him. There is definitely room in the franchise to bring him back.''