Cillian Murphy says Harry Styles has been "really funny" on the set of 'Dunkirk'.

Harry Styles

Harry Styles

The 40-year-old actor will appear alongside the One Direction singer in Christopher Nolan's upcoming World War II movie and the 'Peaky Blinders' star has been enjoying a laugh and a joke with his co-star in between scenes.

He said: "Harry Styles is great.

"I had very few scenes with Harry but we got to hang out and I've got to say he's a great, great kid, and really, really funny.

"Above all, Chris Nolan knows talent and would have cast Harry for a reason."

The Irish actor started his career as a rock musician but turned down a record deal and went on to forge an acting career, which he kick-started in play 'Disco Pigs' in 1996.

While Cillian is remaining tight-lipped about the 'Dunkirk' plot, he thinks the motion picture will be "pretty powerful" and believes Harry will be "terrific" in the drama film.

He added to Radio Times magazine: "There's a long history of musicians moving over into acting and I come from that world myself, so I'm sure he'll be terrific in the role. I trust Chris implicitly in that.

"With the way Chris is shooting, all on IMAX 65mm cameras and in the real locations, it should be pretty powerful.

"The reason why Chris has always been so - quote unquote - 'secretive' about his scripts is that it just ruins the experience. And I agree with him.

"The word 'spoiler' says it all. The anticipation is amazing."

Cillian previously admitted he hasn't been giving Harry advice on set because he doesn't think he's old enough to dish out help to younger stars just yet.

He said: "I hope I'm not in the 'elderly actor giving advice' bracket yet. That would give me a pain in the hole, to be honest."