Zack Snyder reveals how a 'Dawn of the Dead' joke inspired his 'Army of the Dead' zombies.

The 55-year-old filmmaker made his feature film debut in the 2004 remake of George A. Romero's iconic 1978 horror movie, and a running joke on set helped shape the Alphas in his new Netflix flick.

He told SFX magazine: "One of the things that has always really struck me as funny is that zombies can't operate a doorknob, right? Of course that's an over-simplification.

"But zombies at their worst, they're like bad weather, you know what I mean? They're not really a force of intelligence at all and so rudimentary barricades work against them.

"We would always laugh when we were making 'Dawn', like, 'What if a zombie turned a doorknob?' Everyone would be like, 'Oh no! That's horrible!'

"That's the thing that you can't have happen, right? So [the Alphas] kind of started for me there."

The new zombie heist film - which stars former WWE wrestler Dave Bautista as mercenary Scott Ward - has been in the pipeline for a while.

However, Snyder has denied the idea it was ever planned to be a follow-up to his version of 'Dawn of the Dead'.

He added: "No, it was always intended to be set in its own world. I thin if I was ever going to have done a sequel to 'Dawn', it would have been a 'Day of the Dead' remake, something that sort of stayed more in that George Romero world.

"That just makes more sense to me. And so 'Army of the Dead' was always its own thing where I thought, 'If I were to do this from scratch, what would I do with it?' "

The two films have connections behind the scene, including Netflix's Scott Stuber.

Snyder added: "Scott produced on 'Dawn' and we were just talking and I said, 'Y'know, I have this thing, it's like a zombie heist in Vegas.' And he was like, 'What?'

"I think the idea stuck around for so long because it's such a simple, cinematic sort of idea. A team of zombie killers go into Las Vegas to crack a safe and get out with the money. Okay, sure! That sounds like a movie!"