Best actor winner Will Smith smacked presenter Chris Rock in the face and shouted vulgarity at the comedian for making a joke about his wife's hairstyle in a shocking moment overshadowing the Oscars ceremony on Sunday.

About 45 minutes later, when accepting his first Oscar for best actor for his role in King Richard, Smith apologised to the Academy of Motion Picture Arts and Sciences and his fellow nominees in a tear-filled speech, but not to Rock.

"I want to be...