James Gunn has finished writing the 'Guardians of the Galaxy' sequel.

The 44-year-old director has revealed he's already created a follow-up story to the hit 2014 sci-fi adventure film and admits he's ''very excited about it''.

He said: ''Well, I'm really inspired. The whole story is written. I'm very excited about it. And that's where it is. But the story point for me is, in a lot of ways, the most difficult thing.

''I feel like it's pretty strong. It's constantly shifting, but I feel it's pretty strong. I'm excited about it.''

The 'Dawn of the Dead' writer claims the sequel will be very different to the original film, as he thinks that's necessary if the characters - including Chris Pratt's Peter Quill and Zoe Saldana's Gamora - are to develop.

Gunn explained to Comic Book Resources: ''Really, it's just about going forward in an elegant manner. When you go forward with a group of characters, that means you have to go forward.

''And going forward means you're understanding these characters in a new way, you're developing a new kind of story about their lives and who they are and where they're going.

''And if you're doing that, if you're walking forward, then you can't just repeat what you did before. That's going backwards. That's not understanding the character.''

'Guardians of the Galaxy' expanded the Marvel Comics cinematic universe into the cosmos, where adventurer Peter Quill found himself the object of a bounty hunt after stealing a mysterious orb, wanted by a powerful villain named Ronan.