The quantum-locked hunters first appeared in series three episode 'Blink', which featured Carey Mulligan as Sally Sparrow.
After the stone figures were seen in a trailer for the show's return, Moffat told BBC Breakfast: "Those scary statues, I should warn you - and your children - are on their way back and they're way way worse this time.
"How we do we maintain the gripping storylines? Just you wait and see! I'm just dying to get back to that dubbing suite, because I've just seen what the Daleks are up to, and I'm worried."
When asked which other foes The Doctor would face in the upcoming series, he added: "Soon you'll see him grappling with Silurians, an enemy from Jon Pertwee's time as The Doctor, who have a particular reason for wanting to take over the earth - and brand new monsters too."
> Moffat: 'Matt is going to be gorgeous'