PriceWaterhouseCoopers, the accounting firm responsible for tabulating Oscar ballots, apologised for an "error" in the presentation of the best picture award, saying Warren Beatty and Faye Dunaway were handed the wrong envelope.

The embarrassing mix-up saw the Oscar incorrectly given to musical "La La Land" before the actual winner, coming-of-age drama "Moonlight," was finally handed the prize.

The La La Land team was in the middle of their acceptance speeches when the mistake was discovered and rectified.