Screen veteran Donald Sutherland was so innocent when he met marijuana-loving director Robert Altman, he thought the smell of cannabis came from "smoke effects" on set.

The 70-year-old actor shared a volatile relationship with Altman on the set of 1970's MASH, not least because the maverick film-maker attempted to fire him.

But their main difference stemmed from their difference in attitude towards drugs, and Sutherland's straight-laced persona failed to impress Altman and his regular film crew.

Sutherland explains, "I had come from a different kind of tradition. I didn't even know what smoking dope was.

"I literally didn't know what the smell was. I thought it was smoke effects for the movie!

"I was much more rigorous and rigid and less loosey-goosey than Bob's regular people."