Visitors to the set of Star Wars Episode VII at Pinewood, West London, have been warned not to blab about what they see.

And the filmmakers have taken a creative approach to the subject, utilising a propaganda-style poster by artist Cliff Chiang to urge people to keep schtum.

Featuring an imperial officer with his mouth being muffled by a gloved hand, the poster features the tagline: "Loose lips bring down starships."

The poster was shared with the world by movie producer Frank Marshall, who posted a snap of it on Twitter and wrote: "Excited to be here at Pinewood, but mum's the word."

Marshall is married to Lucasfilm big cheese Kathleen Kennedy.