The accountancy firm at the centre of the biggest blunder in Oscars history is to continue its role as the official auditors of the Academy Awards, it has been confirmed.

A mixup by accountants PricewaterhouseCoopers (PwC) at the 89th Academy Awards on 26 February led to a major embarrassment as presenters Warren Beatty and Faye Dunaway incorrectly announced La La Land as the winner in the Best Picture category.

As the delighted cast and crew of the Damien Chazelle-directed romantic comedy, took to the stage of the Dolby Theatre and began to make their acceptance speeches, it became clear something was amiss.

"I'm sorry, there's a mistake," said Beatty addressing the gathering of A-listers and a viewing audience of millions.

"I opened the envelope and it said 'Emma Stone, La La Land'. I wasn't trying to be funny," he said.

As the error became apparent it was revealed that the real winner of the Best Film Oscar was, in fact, Moonlight. This prompted La La Land producerJordan Horowitz graciously to invite the rightful recipients, director Barry Jenkins and the film's cast and crew, to accept the award from him.

It later emerged that the veteran presenters had been handed the wrong cue card by accountants Brian Cullinan and Martha Ruiz, who were responsible for counting the votes and personally handing the closely guarded envelopes to each award presenter just before they walked on stage .

The Oscars 2017
'La La Land' producer Fred Berger (R) speaks at the microphone as production staff consult behind him regarding a presentation error of the Best Picture award (later awarded to 'Moonlight') onstage Kevin Winter/Getty Images

Cullinan, who has been an accountant at PwC for 32 years, had mistakenly handed the back-up envelope for best actress in a leading role to the presenters. He committed the error after becoming distracted as he took a photo of La La Land star Emma Stone, who had just won the prize for best leading actress.

Despite strict guidelines which prohibit PwC staff from taking photos at the event, the evidently starstruck Cullinan posted the image on his personal Twitter account. He later deleted it.

The incident, dubbed 'envelopegate', has gone down as the biggest Oscars blunder in the awards' 89-year history. Reflecting on the unfortunate episode, Academy president Cheryl Boone Isaacs told AP that "the last 90 seconds" of the telecast overshadowed "the most brilliant and wonderful show" and vowed that changes would be made following a review.

On Wednesday (29 March), the Academy of Motion Picture Arts and Sciences announced that, despite the fiasco, they will retain the services of PricewaterhouseCoopers (PwC), who have overseen the Oscars ballot for 83 years.

President Cheryl Boone Isaacs wrote a letter to Academy members explaining that the Academy had been "unsparing in our assessment that the mistake made by representatives of the firm was unacceptable.

"After a thorough review, including an extensive presentation of revised protocols and ambitious controls, the Board has decided to continue working with PwC," a statement read.

The Oscars 2017
Producer Jordan Horowitz holds up the card for the Best Picture winner, Moonlight Lucy Nicholson/Reuters

While Cullinan and Ruiz have been removed from Oscars duty, having been banned from the ceremony for life, two new accountants will be tasked with the responsibility of handing out the winner's envelopes at the 90th Academy Awards.

A third accountant will oversee the announcements from the control room, in order to notify the director in the event of another mistake.

As a further precaution, all accountants involved in the event will be required to to hand over their phones and other electronic devices before going backstage, Reuters reports.

While both Cullinan and Ruiz continue to work for PWC, they have been afforded increased security at their homes after receiving death threats on social media following the debacle.