The pair made the announcement at a special BFI screening for the fantasy drama's fourth series premiere.
"Julian and I are in discussions at the moment about whether or not to do a Merlin movie," confirmed Capps.
No further details about the film project are known, though the show's original cast - includingColin Morgan, Bradley James and Katie McGrath - are expected to star.
A fourth series of Merlin is currently wrapping up filming in Wales and will begin on BBC One next month.
A fifth run has already been commissioned, with Capps claiming that the advance pick-up will allow future episodes to focus on "slow-burn" character arcs.
> Merlin returns: The fourth series premiere in pictures
Watch Merlin star Katie McGrath give Digital Spy a tour of the show's set below:
link to this article on DigitalSpy.com