The film has made $93 million in ticket sales in the US alone in its opening weekend - the biggest ever February opening.
Outside of the US, author EL James, with whom she is said to have a tempestuous relationship.
The director has refused to comment the speculation, adding: "All press reports are pure conjecture as the studio have not committed to a sequel as yet.
News of Hunnam's departure from the film broke in November 2013 and Dornan was swiftly enlisted as his replacement."For the first time in my life, [I] had more work than I had time to do it," Hunnam told .
"It's very hard to be disciplined in that situation and understand what is going to be required to all of that work to the best of your ability and have yourself surrounded by people."He decided to avoid burning out and continued filming television show "You see it all the time in Hollywood," he added.