Warren Beatty has urged the organisers of the Oscars to "publicly clarify" the reasons for the envelope mix-up which led to the highest-profile fiasco in the ceremony's history.
The climax of the Academy Awards fell victim to chaos and confusion as La La Land was mistakenly named the winner of the best picture gong.
The stars and producers of the hit film were completing their acceptance speeches when one of the musical's producers, Jordan Horowitz, took to the microphone to reveal the mix-up.
Coming-of-age drama Moonlight was the real victor of the top prize.
Beatty, who presented the award alongside his Bonnie And Clyde co-star Faye Dunaway, was given the card for actress in a leading role rather than the best picture winner.
He issued a statement to Associated Press encouraging president of the Academy of Motion Pictures, Cheryl Isaacs, to comment on the incident.
Declining to speak out further on the debacle, Beatty said: "I feel it would be more appropriate for the president of the Academy, Cheryl Boone Isaacs, to publicly clarify what happened as soon as possible."
Although the academy issued a statement apologising for the mix-up, it has largely left it to accountant firm, PricewaterhouseCoopers (PwC), who are responsible for the ballot, to explain how it happened.
Tim Ryan, US chairman and senior partner at PwC, told Variety magazine Brian Cullinan, one of two accountants responsible for the presenters' envelopes, gave Beatty the wrong one as the Hollywood star took to the stage with Dunaway.
"There's a stack for the back-ups and the ones that are not the back-ups and he took from the wrong stack," he said.
Mr Ryan told the magazine Mr Cullinan, chairman of PwC's US board, was left feeling "very, very terrible and horrible" and repeated the firm's apologies for the historic mix-up.
The global accountancy company, which has held the coveted role of overseeing the ballot for 80 years, swiftly launched a post mortem of the incident on Sunday night.
It was reportedly the fourth year Mr Cullinan had been responsible for handing out the envelopes, the contents of which are known only by the two PwC employees handing them out on the night.
Mr Cullinan, standing stage left, and colleague Martha Ruiz, in the wings, each had a pile of envelopes for presenters entering from their side of the stage, Mr Ryan said.
The accountants also had a "back-up" of envelopes for their colleague on the opposite side.
It was from this pile that Mr Cullinan mistakenly picked up the best actress envelope and handed it to Beatty.
The two accountants were forced to intervene on stage amid the confusion and chaos and it later emerged Mr Cullinan had tweeted a behind-the-scenes photo of best actress winner Emma Stone moments before the best picture announcement.
The tweet was later deleted.
Neither PwC or the academy has revealed whether his use of social media was a factor in the error.