INTERNATIONAL: Before Will Smith picked up his Oscar for best actor, comedian Chris Rock made a joke at wife Jada's expense while presenting the best documentary prize. This is the moment Will Smith has interrupted the 94th Academy Awards ceremony.

The awards ceremony was, according to commentators, "upstaged" by an incident in which Will Smith has slapped Chris Rock on-stage over a reference to his wife, Jada Pinkett-Smith.

Will Smith has smacked presenter Chris Rock in the face with an open hand and shouted a vulgarity at the comedian for making a joke about his wife's appearance at the Oscars ceremony on Sunday ,March 28, at the Dolby Theatre in Los Angeles.

Rock made a joke about the hairstyle of Smith's wife Jada Pinkett Smith that referenced the movie "G.I. Jane" in which actress Demi Moore shaved her head. Jada Pinkett Smith's has a hair condition and why Chris Rock's 'joke' didn't go down well. She has a very real condition called alopecia areata, is an autoimmune disorder that causes hair to fall in clumps. There are different types of alopecia and it usually occurs in women aged 30-50. The condition is different for different people. Some people lose hair in only a few areas, others lose a lot and for some, it gets better on its own. This can be due to genetic reasons or a history of baldness in the family.

Smith, who won for best actor for "King Richard," afterwards, has walked on stage and slapped Rock in what at first appeared to be a scripted joke. But the mood has turned somber moments later when Smith, back in his seat, shouted back, "Keep my wife's name out of your fucking mouth."