Reitman, whose latest movie No Strings Attached debuts in the UK this Friday, confirmed to Digital Spy that Murray has the script for the sequel.
"He's seen it and we're waiting to hear," Reitman said.
"He's seen the cover of it!" interjected the filmmaker's No Strings Attached star Asthon Kutcher.
"Thank you for putting that so well," Reitman added. "Fingers crossed!"
Asked if Kutcher could star as one of the new generation of Ghostbusters in the proposed movie, Reitman said that the idea was "absolutely possible".
Click 'play' below to watch Ivan Reitman discuss Ghostbusters 3:
> Click here to watch our full interview with Ashton Kutcher and Ivan Reitman