Idris Elba has said he cannot watch Luther – because it is too dark.

The 46-year-old star is returning to the BBC One drama for a fifth series, beginning on New Year’s Day.

And he said: “I try not to watch the show. It’s dark, very dark.”

The Sun quoted the actor, who has a four-year-old son, as saying: “I’ve got my son so we just watch Shrek.”

He has also spoken of plans to make a Luther film.

“We’ve got the skeleton of an idea,” he said. “This series has the film very much in its sights.”

The fifth series of Luther premieres on New Year’s Day on BBC One and BBC iPlayer – and will be broadcast over four consecutive nights.