Mel Gibson has defended The Birth of a Nation director Nate Parker over the fallout from the latter’s arrest and trial on rape charges in 1999, which has overshadowed the release of Parker’s film.

Gibson was speaking at a Hollywood Reporter event that was timed to coincide with the magazine’s awards-season coverage, appearing with fellow directors Mira Nair (Queen of Katwe), Denzel Washington (Fences), Oliver Stone (Snowden), Damien Chazelle (La La Land) and Barry Jenkins (Moonlight).

Invited to comment on if it was fair that filmgoers may have avoided The Birth of a Nation due to the controversy surrounding Parker, Gibson said: “I don’t think it’s fair. He was cleared of all that stuff [Parker was found not guilty]. And it was years ago. You have to follow the system there.”

Gibson added: “I think he’s innocent of all that stuff. The fact that he has to live with that stigma, and that it affects the art he does, is unfair.”

Parker was accused of rape in 1999 along with Jean Celestin (who shares a story credit with Parker for The Birth of a Nation) by a fellow student at Pennsylvania State University. Parker was acquitted and Celestin convicted of sexual assault. The latter’s conviction was overturned in 2005 and a retrial was abandoned due to a large number of witnesses being unavailable. Parker’s accuser killed herself in 2012.

The Birth of a Nation, which tells the story of the 1831 slave rebellion led by Nat Turner, was a disappointment at the US box office, taking $15.8m (£12.53m) after being acquired for $17.5m by Fox Searchlight. Fox expects to lose $5m to $10m on the film.