John Landis had to turn "psychopaths into romantics" on 'Burke & Hare'.

The director - who cast Simon Pegg and Andy Serkis as real life 19th century killers William Burke and William Hare in the movie - confesses the grisly realism of their 17 murders committed by the pair between 1827 and 1828 had to be "balanced" with the needs of a 21st century movie.

He said: "It is a very delicate balancing act that we need to do in the movie, because really these two were terrible men, really evil, but we're aiming for a very, very black comedy and to make it work we need the audience to like them.

"We're turning these psychopaths into romantic leading men."

Landis - best known for directing 'An American Werewolf in London' and 'The Blues Brothers' - also admits he has been offered lots of "stupid" comedy work recently, leading to him taking a step back from bigger productions.

He told the Daily Telegraph: "I've been working constantly, I just haven't made a big movie.

"But with 'Burke & Hare' I decided I wanted to go back to working on a bigger picture. I had been so fed up with studio people - everyone wanted to give me stupid comedies.

"Now I like comedy, it is just that everything was so stupid and banal. Really, in the last 10 to 12 years there's no really big film studios that is now owned by an international conglomerate, becoming a small part of a super corporation.

"That has changed the bottom line and the product really reflects it."