Mark Hamill has l revealed why his 'Star Wars' character Luke Skywalker went into exile.

The 65-year-old actor briefly reprised the role of the iconic Jedi in 'Star Wars: The Force Awakens' and is set to play a pivotal role in the next instalment 'The Last Jedi' this December, but the actor has revealed why his alter-ego was so riddled with "guilt."

Speaking to Entertainment Weekly, Hamill said: "Luke made a huge mistake in thinking that his nephew was the chosen one, so he invested he had in Kylo, much like Obi-Wan did with my character.

"And he is betrayed, with tragic consequences. Luke feels responsible for that. That's the primary obstacle he has to rejoining the world and his place in the Jedi hierarchy, you know?

"It's that guilt, that feeling that it's his fault, that he didn't detect the darkness in him until it was too late."

The actor, who starred in the original trilogy alongside Harrison Ford and the late Carrie Fisher, had a hard time when reading the script as to why his character wanted to end the Jedi.

He said: "When I first read it, my jaw dropped. What would make someone that alienated from his original convictions? That's not something that you can just make up in an afternoon, and I really struggled with this thing."

The returning cast includes John Boyega (Finn), Oscar Isaac (Poe Dameron), Adam Driver (Kylo Ren), Lupita Nyong'o (Maz Kanata), Gwendoline Christie (Captain Phasma), Dohmnall Gleeson (General Hux), Anthony Daniels (C-3PO), Andy Serkis (Snoke) and the late Fisher as General Leia, while Benicio Del Toro, Laura Dern and Kelly Marie Tran are all newcomers to the franchise.

'Star Wars: The Last Jedi' is slated to be released this December.