William said he was left with “indescribable sadness” to know the corporation’s shortcomings had “contributed significantly” to Diana, Princess of Wales’ state of mind in the final years of her life.
“She was failed not just by a rogue reporter, but by leaders at the BBC who looked the other way rather than asking the tough questions,” the duke said.
The Duke of Sussex in a separate statement said about his mother: “The ripple effect of a culture of exploitation and unethical practices ultimately took her life.”
An inquiry found the BBC covered up “deceitful behaviour” used by journalist Martin Bashir to secure his headline-making world exclusive interview with Diana, and “fell short of high standards of integrity and transparency”.
The journalist was in “serious breach” of the BBC’s producer guidelines when he faked bank statements and showed them to Earl Spencer to gain access to the princess in 1995, a report by Lord Dyson said.
The future king said his mother’s appearance on Panorama contributed to “making my parents’ relationship worse”.
William called for the documentary never to be aired again and said the BBC’s failings had not only let his mother and family down but the public as well.
The BBC has written to the royal family to apologise for the circumstances surrounding the interview.
Personal expressions of regret have been sent to the Queen, Prince of Wales, the dukes of Cambridge and Sussex, and Diana’s brother Earl Spencer.
William said in his statement: “The interview was a major contribution to making my parents’ relationship worse and has since hurt countless others.
“It brings indescribable sadness to know that the BBC’s failures contributed significantly to her fear, paranoia and isolation that I remember from those final years with her.
“But what saddens me most, is that if the BBC had properly investigated the complaints and concerns first raised in 1995, my mother would have known that she had been deceived.”
He ended with the words: “In an era of fake news, public service broadcasting and a free press have never been more important. These failings, identified by investigative journalists, not only let my mother down, and my family down; they let the public down too.”
Harry praised Diana in his statement statement: “Our mother was an incredible woman who dedicated her life to service. She was resilient, brave, and unquestionably honest.
“The ripple effect of a culture of exploitation and unethical practices ultimately took her life.
“To those who have taken some form of accountability, thank you for owning it. That is the first step towards justice and truth. Yet what deeply concerns me is that practices like these — and even worse — are still widespread today.
“Then, and now, it’s bigger than one outlet, one network, or one publication.
“Our mother lost her life because of this, and nothing has changed. By protecting her legacy, we protect everyone, and uphold the dignity with which she lived her life. Let’s remember who she was and what she stood for.”