Kenyan actress Lupita Nyong'o's shocked reaction to Will Smith clashing with Oscars host Chris Rock at Sunday night's ceremony is trending on social media.

Smith slapped Rock after the comic made a joke about the actor's wife Jada Pinkett Smith, saying "Jada, can't wait for GI Jane 2," in an apparent reference to her shaved hairdo - which is a result of the hair loss condition alopecia.

Smith walked on stage and struck Rock before returning to his seat and shouting: "Keep my wife's name out of your [expletive] mouth."

Nyong'o's apparent realisation that the altercation wasn't a stunt was captured live on camera:

All the world is Lupita Nyong’o in this very moment pic.twitter.com/h6S7lSF0Mq

— motodave 🦋🏍 (@majiddave) March 28, 2022

Lupita wins Best Actress for being the Middle Woman in Chris vs Will

— queen priyanka - stream taste test (@thequeenpri) March 28, 2022

LUPITA IN THE BEHIND WILL SMITH IS KILLING ME #AcademyAwards pic.twitter.com/4AvFQ4ZgDT

— Ghana 🇬🇭 🇬🇭🇬🇭🇬🇭🇬🇭🇬🇭🇬🇭 (@nowell__blacko) March 28, 2022

Smith later apologised to the awards body and to his fellow nominees while accepting his Oscar for best actor, but there was no specific apology for Rock.

The Los Angeles Police Department later told Variety that Rock had "declined to file a police report" following the event.

The Academy of Motion Picture Arts and Sciences, which organises the Oscars, tweeted that it "does not condone violence of any form".