“This is a sad day for the BBC. Tim has been an outstanding Director-General for the last five years. He has propelled the BBC forward with determination, single-mindedness and foresight.
“He has had the full support of me and the Board throughout. However, I understand the continued pressure on him, personally and professionally, which has led him to take this decision today. The whole Board respects the decision and the reasons for it.
“Tim has given 20 years of his life to the BBC. He is a devoted and inspirational leader and an absolute believer in the BBC and public service broadcasting. He has achieved a great deal. Foremost, under his tenure, the transformation of the BBC to meet the challenges in a world of unprecedented change and competition is well underway.
“Personally, I will miss his stamina, good humour and resilience and I will miss working with him. I wish him and his family the very best for the future.
“This is an important time for the Corporation and the Board and I will continue to work with Tim in the interim while we conduct the process to appoint his successor.
“I want to thank Deborah for her leadership of BBC News over the past three years. She has transformed the operation of News with real commitment and a clear vision of the future.
“She has acted with integrity in challenging circumstances and leaves a strong legacy from which to build for the many millions around the world who rely on and trust the voice of BBC News every day.”