Ewan McGregor has stepped up to defend fellow Scottish actor James McAvoy over criticisms theatre bosses are "dumbing down" by hiring him to star in a new London production of Macbeth.

The X-Men: First Class star is currently playing William Shakespeare's tragic king at the Trafalgar Studios in the British capital, and his performance was discussed by famed theatre director Jonathan Miller in an episode of the Bbc's Hardtalk Tv show on Monday morning (25Mar13).

Host Stephen Sackur asked Miller whether theatre bosses are "dumbing down" by hiring Hollywood actors such as MCAvoy to lead highbrow productions, and the director replied, "Yes, I think it might be... I suspect... that if you are only interested in casting celebrities, the chances are that you are not interested in directing the negligible details of reality (in theatre)...

"There is a preoccupation with celebrity and I think an awful lot of young people have become seduced by famous names and they will go to see someone who is famous rather than engaging in the (theatre experience)..."

The comments have riled MCGregor, who has now spoken out in defence of MCAvoy and called the criticisms "ridiculous".

In a post on Twitter.com, he writes, "Hardtalk moaning about celebs in theatre. Using James MCAvoy as an (example). Ridiculous. Don't they know he's a brilliant actor. Come on Bbc!"