Chris Columbus says a 'Mrs. Doubtfire' sequel would be "impossible" without Robin Williams.

The 63-year-old filmmaker - who was at the helm of the beloved 1993 comedy which starred the late actor as a nanny called Euphegenia Doubtfire - has addressed speculation over a potential follow-up after the launch of a Broadway musical based on the film this week.

Speaking to SF Gate, Columbus said: "It's impossible. It's just impossible.

"I just was reading a lot of reviews, ironically, today and about the Broadway show [which opened in New York this week].

"And this guy who's playing him [Rob McClure] is supposedly very energetic and phenomenal. But he's no Robin. Robin was one-of-a-kind."

Williams took his own life at his home in August 2014 aged 63, and Columbus admitted there were plans for a sequel before his the actor's death.

He added: “The last time I met with Robin before he passed away was about the ‘Mrs. Doubtfire’ sequel.

“We had a script, and it was a great script. Robin was prepared to do it. And then, unfortunately, he passed away.”

Meanwhile, the director previously confirmed the existence of an R-rated version of the movie as they shot a number of alternative scenes.

He said: "The reality is that there was a deal between Robin and myself, which was, he’ll do one or two, three scripted takes.

"And then he would say, ‘Then let me play.’ And we would basically go on anywhere between 15 to 22 takes, I think 22 being the most I remember.

"He would sometimes go into territory that wouldn’t be appropriate for a PG-13 movie, but certainly appropriate and hilariously funny for an R-rated film."

Despite this, he doesn't expect the alternative version of the movie to ever be seen by an audience.

He explained: "I would be open to maybe doing a documentary about the making of the film, and enabling people to see certain scenes re-edited in an R-rated version.

"The problem is, I don't recall most of it. I only know what's in the movie at this point because it's been a long time. But I do remember it was outrageously funny material."