'Ghostbusters 3' will be scrapped if Bill Murray refuses to sign up.

Plans for a third instalment in the franchise have been mooted for several months, but now Sigourney Weaver has admitted she and the rest of the cast of the first films are unlikely to go ahead with the project if the actor - who has previously said he hasn't read The Script - won't take part.

Asked if there were any updates on the project, Sigourney said: "I guess Bill [Murray] hasn't read the script yet.

"I don't think any of us would do it if Bill said no. Why would we do that? I think the whole point is to get together and have fun."

Despite the Delays, Sigourney insists she would never call Bill about the film as she has learned to understand whether or not he is interested in a project.

She said: "I would never do that [call him about it]. I don't think that works with Bill. I did actually ask him about The Guys, because he did it with me originally. I called the 800 number and left the message. And when he doesn't respond, then you know that he's not interested. It's actually a pretty good system. I envy him in a way. No email, no phone calls, no agent, I don't know what he does."