In a letter to staff, Davie said quitting the job after five years “is entirely my decision.”
“Overall the BBC is delivering well, but there have been some mistakes made and as director-general I have to take ultimate responsibility,” Davie said.
He said that he was “working through exact timings with the Board to allow for an orderly transition to a successor over the coming months.”
Turness said that the controversy about the Trump documentary “has reached a stage where it is causing damage to the BBC – an institution that I love. As the CEO of BBC News and Current Affairs, the buck stops with me.”
“In public life leaders need to be fully accountable, and that is why I am stepping down,” she said in a note to staff. “While mistakes have been made, I want to be absolutely clear recent allegations that BBC News is institutionally biased are wrong.”