Diana died in a car crash two years later in 1997.
Now, 25 years later, a 127-page report was published after an inquiry was done into the interview. It found that Bashir had used falsified bank statements in order to persuade Diana's brother, Charles Spencer, to grant him a meeting with the princess.
It was at this meeting that Bashir persuaded Diana to give the interview. The fake bank statements suggested that Diana was bugged and her two senior aides were paid to provide information on her.
In a statement, Prince William said: "It is my view that the deceitful way the interview was obtained substantially influenced what my mother said. 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."
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The investigation was set up by the BBC and was headed by former senior judge John Dyson after Spencer's allegations of being tricked by Bashir.
After the interview was aired, Bashir proceeded to lie to his bosses repeatedly about how he managed to acquire the interview. His bosses reportedly did not look too hard at the details and then covered up facts about how he was able to get the interview.
According to the inquiry, the BBC fell short of the "high standards of integrity and transparency which are its hallmark."
The BBC has since written an apology to Buckingham Palace and Bashir apologised for the fake statements. However, he reportedly stands by the evidence he gave 25 years ago and said he does not believe it prompted Diana to give him the interview.
"[Diana] 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. These failings, identified by investigative journalists, not only let my mother down, and my family down; they let the public down too," said William who added that the BBC should have done a proper investigation when concerns were raised 25 years ago.
Prince Harry has also issued a response about the revelations. He said: "Our mother lost her life because of this."
He continued by saying that the "ripple effect of a culture of exploitation and unethical practices" ultimately led to the death of Princess Diana.
Harry then added that the press still engages in these types of unethical practices and that the problem is bigger than just a single outlet or publication.
"Nothing has changed. By protecting her legacy, we protect everyone, and uphold the dignity with which she lived her life," Harry said.
Related: Prince Harry Says He Was Caught in a Cycle of “Pain and Suffering” in the British Royal Family
