Actor Viggo Mortensen attends the AFI Fest Screening Gala for "Green Book" in Hollywood on November 9, 2018. / AFP / VALERIE MACON Image Credit: AFP

Actor Viggo Mortensen has apologised for using a racial slur during a panel discussion about his new film Green Book.

Mortensen, who is white, appeared on Wednesday at the event with his co-star, Mahershala Ali, and director Peter Farrelly.

Mortensen told The Hollywood Reporter on Thursday he was making the point that many people casually used the slur in 1962, when the movie takes place. He says he had “no right to even imagine the hurt that is caused by hearing the word in any context.” He says he intended to “speak strongly against racism” and is sorry he used the word.

In Green Book, Mortensen’s character is hired to drive an African-American pianist on a concert tour in the South.

The movie is due in US theatres later this month.