A film version of the popular Fox drama has been in development since the show ended in 2010.
"I've been working very hard to make that happen," Sutherland is quoted as saying by Yahoo. "The process has taken us so long because it's such a complicated script to write."
He explained: "Normally, we have 24 hours to tell a story. Trying to condense it into two hours involves a lot of hard choices: What kind of story do you want to tell? How political do you want to make it? How character-driven do you want to make it?"
Sutherland added that he is keen to recruit a director and begin casting the movie adaptation.
"The film will pick up with Jack Bauer six months after the end of the final TV episode," he confirmed. "We still need to find a director and see which actors from the series would be available to return to do the film with me."
> Kiefer Sutherland: 'I couldn't find work after 24'
> Kiefer Sutherland: '24 movie will shoot in 2013'
The 45-year-old actor - who first played Jack Bauer in 2001 - also dismissed the suggestion that interest in a 24 film is lessening the longer it takes the project to materialise.
"I think audiences still remember the series and have a huge interest in seeing what a film version would be like," he insisted. "People still tell me how much they loved Jack Bauer and I think audiences appreciated that he wasn't a typical hero-type and had many flaws and contradictions.
"We'll also have a lot more creative freedom and possibilities doing the film as opposed to the kinds of limitations you have when doing a TV series in real time."
Watch Kiefer Sutherland discuss the 24 movie with Digital Spy below: