LONDON -- BBC Director-General Tim Davie and CEO of News Deborah Turness have resigned following criticism that a BBC documentary misled viewers by editing remarks made by US President Donald Trump, the broadcaster announced Sunday.

The resignations came ahead of the BBC's expected apology over the controversy on Monday.

"I wanted to let you know that I have decided to leave the BBC after 20 years," Davie said in his resignation statement, adding that "there have been some mistakes made and as director-general I have to take ultimate responsibility."

The controversy centered on the Panorama documentary "Trump: A Second Chance?" aired last year. The program was criticized for splicing together clips of Trump's speech on Jan 6, 2021 in a way that allegedly gave the misleading impression that he urged his supporters to march to the US Capitol and "fight like hell."

The Telegraph reported on Nov 3 that a leaked internal BBC memo by Michael Prescott, a former independent external adviser to the broadcaster's editorial standards committee, flagged the issue.

Culture Secretary Lisa Nandy said Sunday that there were a series of "very serious allegations" that had been made about the BBC, "the most serious of which is that there is systemic bias in the way that difficult issues are reported at the BBC."

"I've spoken to the chair (of the BBC) this week, I am confident that he is treating this with the seriousness that this demands," she said when appearing on a BBC current affairs program.