The Academy of Motion Pictures Arts and Sciences issued a statement following a board meeting to discuss new protocols for the voting and winner announcements.

Cheryl Boone Isaacs, the Academy’s president, said: ‘After a thorough review, including an extensive presentation of revised protocols and ambitious controls, the board has decided to continue working with PwC.’

Boone Isaacs said Academy members have ‘been unsparing in our assessment that the mistake made by representatives of the firm was unacceptable.’

The Academy said it was retaining PwC services, but that current ‘balloting leaders’ Brian Cullinan and Martha Ruiz would no longer be involved. The pair were responsible for the on-screen mix-up which saw veteran actor Warren Beatty handed the wrong envelope at the finale, with the result that he mistakenly announced La La Land the winner of best film, instead of Moonlight.

Under the new rules, from next year, the Academy will ban electronic devices backstage. Cullinan was said to have tweeted a photo of best actress Emma Stone just before the envelope muddle unfolded.

PwC chairman Tim Ryan will play a larger role in overseeing the voting, and the firm will also bring back Rick Rosas, who was one of the two accountants in charge of balloting from 2002 to 2014. In addition, PwC will station a third accountant in the control room. That accountant will know the winners in advance, and will be able to alert the show’s director in case of an error.

The Academy has also said it will improve the identification of the categories on the awards envelopes, while PwC will participate in rehearsals in order to check for ‘for possible on stage problems’.

PwC has handled Oscar balloting for 83 years, in addition to doing the Academy’s taxes and audits.