LONDON (AP) — A British television channel on Monday defended its decision to broadcast recordings of Princess Diana candidly discussing her personal life, after some royal watchers called it a betrayal of the late princess' privacy.

Channel 4 said the video tapes, made in the early 1990s, are an "important historical source" and place Diana "front and center" in her own story as Britain marks 20 years since her unexpected death.

The channel said that although the recordings were made in private, "the subjects covered are a matter of public record and provide a unique insight into the preparations Diana undertook to gain a public voice and tell her own personal story."

Diana Spencer married Prince Charles, heir to the British throne, in 1981 and the couple had two sons, Prince William and Prince Harry. They separated in 1992 and divorced in 1996, the year before Diana died in a car crash in Paris, aged 36.

The recordings of Diana talking to voice coach Peter Settelen were made at the princess' Kensington Palace residence, and include discussion of her failing marriage and Charles' relationship with his then-mistress Camilla Parker Bowles. Charles and Camilla went on to marry in 2005.

Rosa Monckton, a friend of Diana, said broadcasting the tapes was "a betrayal of her privacy and of the family's privacy."

Former royal spokesman Dickie Arbiter told Sky News it was "absolutely shameful" that the tapes were being broadcast, saying Diana's family would find it "very hurtful."

Settelen made the recordings at a low point in Diana's life, after she had rocked the royal family by cooperating on a biography that went public with her unhappiness and the failure of her marriage.

The 20 videotapes were held by police after they were seized from ex-royal butler Paul Burrell's home in 2001 during an investigation of alleged theft from the late princess.

The theft case was later abandoned and Diana's family tried to make a legal claim to the recordings, but they were returned to Settelen in 2004.

Portions of the recordings were broadcast by U.S. network NBC in 2004, but they have never been shown in Britain.

They feature in a Channel 4 documentary that is due to air Sunday.

William and Harry's Kensington Palace office declined to comment on the documentary. As the 20th anniversary of Diana's death on Aug. 31, 1997 approaches, the princes have spoken publicly for the first time about their mother and the pain of losing her.