The BBC has apologised after an inquiry found journalist Martin Bashir used deceit to secure an explosive 1995 interview with Princess Diana.
John Dyson, the former senior judge who led the inquiry, concluded that Bashir had shown fake bank statements to persuade Diana's brother Charles Spencer to introduce his sister to him.
He said the BBC "fell short of the high standards of integrity and transparency which are its hallmark".
"The indirect and real target of Mr Bashir's deceptions was Princess Diana," he wrote.
In the Panorama interview, a major scoop for the broadcaster, Diana famously said "there were three of us in this marriage", triggering a major crisis for the royal family. The princess also opened up about her struggle to adapt to royal life and her battle with bulimia.
The BBC made a "full and unconditional apology" for the "clear failings" identified in the report.
"Although the report states that Diana, Princess of Wales, was keen on the idea of an interview with the BBC, it is clear that the process for securing the interview fell far short of what audiences have a right to expect. We are very sorry for this. Lord Dyson has identified clear failings," BBC director general Tim Davie said.
"While today's BBC has significantly better processes and procedures, those that existed at the time should have prevented the interview being secured in this way.
"The BBC should have made greater effort to get to the bottom of what happened at the time and been more transparent about what it knew. While the BBC cannot turn back the clock after a quarter of a century, we can make a full and unconditional apology. The BBC offers that today."
Bashir, who stepped down as the BBC's religion editor last Friday, apologised for the faking of bank documents but believed Diana would have participated in the interview anyway.
"The bank statements had no bearing whatsoever on the personal choice by Princess Diana to take part in the interview," he said.
"Evidence handed to the inquiry in her own handwriting (and published alongside the report today) unequivocally confirms this, and other compelling evidence presented to Lord Dyson reinforces it."
In her handwritten note – dated December 22, 1995, but published for the first time on Thursday – Diana said she had no regrets participating in the interview.
"Martin Bashir did not show me any documents, nor give me any information that I was not previously aware of," she said.
"I consented to the interview on Panorama without any undue pressure and have no regrets."