"Personally, selfishly, we'd all really like to do it, but we are really serious about trying to get the story and the script right," the Daily Star quoted him as telling Britain's Total Film magazine.
He added: "Because the only thing more disappointing than not having another one of these movies is - for us and for movie fans - to make one that isn't good. Everyone would say, They should have quit after three. And we'd feel that way too. We don't have the script yet, but hopefully we'll all be shooting in 18 months or so."