Sam Mendes has revealed that he decided to direct Bond 24 because he felt the story wasn't finished.

The Skyfall director admitted he had doubts about signing up for another instalment, but ultimately chose to do so because he didn't want to leave the plots up in the air, as he spoke to American interviewer Charlie Rose on his TV show, reported Empire.

"I didn't want to do it again initially because I felt first of all, I didn't have time to work (it) out... I also started a number of stories that were incomplete. I cast a new M, I cast a new Moneypenny, I cast a new Q and a new Tanner," he said.

"I felt like there was a way to create a second part of a two-part story, and then I got re-interested when they (producers Michael G Wilson and Barbara Broccoli) agreed to wait a little longer and not go immediately, and not go with two movies but with one, which I felt very strongly about."

Daniel Craig will return as James Bond alongside Ralph Fiennes as M, Naomie Harris as Miss Moneypenny, and Ben Whishaw as Q in the next film, to be written by John Logan.

Bond 24 will be released in October 2015.

Sam - who was inspired to agree to another film after remembering hearing Skyfall's first audience's roar of happiness, which was like the "orgy of nostalgia" - revealed Bond 24 will feel like an indirect sequel to Skyfall.

"I wouldn't say it's the actual narrative but it is (connected)," he continued.

"What we try to do and audiences seem to embrace in Skyfall was that for the first time, characters were allowed to age and they acknowledge the passing of the years and the history of the franchise," he added.