A new generation of actors are failing to learn their lines before they turn up to work, Bill Nighy has said, as he criticises the “discourtesy to their fellow professionals”.

Nighy, the Bafta-winning actor, said it had become fashionable for film and theatre actors to deliberately refuse to learn their lines ahead of time, mistakenly believing it would improve their performance.

Saying actors must refocus their attention on preparing properly, Nighy argued the trend had been propagated by those who simply “don’t want to do their homework”.

The actor, 67, started his career after leaving school with two O Levels, and has gone on to appear in critically-acclaimed works on stage and screen.

Asked for his advice for young actors, he said:“If you’re doing anything, whether it’s a play or a film, learn every single word that you have to say backwards forwards and sideways before you go into a rehearsal room and before you go on a film set.

“That might sound like an obvious thing, but it’s not currently: there is a fashion for not knowing your lines.

“It’s been invented by people who don’t want to do their homework, even as a creative choice.

“You will not become imprisoned by intonations, and therefore it’s a discourtesy to your fellow professionals. “That’s a piece of bull---t from people who don’t do their homework.