The Scottish actor, 41, best known for his roles in Trainspotting, Moulin Rouge! and latterly Ghost and Salmon Fishing in the Yemen, will play the character of Bill Fordham alongside Meryl Streep and Julia Roberts.

The 47 year-old Tracy Letts – who wrote the screenplay for the film –  has quickly established himself as one of the most exciting writers working in Hollywood due to his collaboration with Exorcist director William Friedkin on the 2006 film Bug and then this year’s Killer Joe.

Loosely based on Alexandre Dumas’ 1848 play Camille, August: Osage County centers on the waning days of Meryl Streep’s sharp-tongued prescription-drug taking mother who is surrounded by a cast of eccentric family members and hangers-on, each of whom vie for her attention.

Roberts is to play Streep’s daughter Barbara while Juliette Lewis, Abigail Breslin and Dermot Mulroney also star. Benedict Cumberbatch is rumoured to be in negotiations for a role.

John Wells is directing the project, which has been adapted for the screen by Letts, while George Clooney and Grant Heslov will be producing along with Harvey Weinstein,  The film will be distributed by The Weinstein Company.

McGregor was most recently seen in Haywire and Salmon Fishing in the Yemen. He will next be seen in Jack the Giant Killer alongside Nicholas Hoult.