The Oscars was plunged into chaos as La La land was mistakenly announced as the best picture with the actual winner being Moonlight.

In a historic Academy Awards upset Warren Beatty read out the wrong winner.

Shock spread through the Dolby Theatre when producers of "La La Land" were stopped in the middle of their acceptance speeches to be informed that Beatty had incorrectly read "La La Land" as the winner.

Host Jimmy Kimmel came forward to inform the cast that "Moonlight" had actually won, showing the inside of the envelope as proof. "I knew I would screw this up," said Kimmel, a first-time host. "I promise to never come back."

Beatty explained on stage immediately after the mistake was realised "I wasn't trying to be funny".

He said he had seen the name Emma Stone from "La La Land" when he opened his envelope.

Producer Jordan Horwitz then graciously passed his statue to the "Moonlight" producers.

Moonlight tells the story of a boy's journey to adulthood through his rough upbringing in Miami.

The film stars Naomi Harris as the boy's drug-addicted mother, and Mahershala Ali as a drug dealer-turned mentor for the boy.

"Moonlight" has provided some of the stiffest competition during Hollywood's awards season for the musical "La La Land," which was nominated for a history-tying 14 Academy Awards.