Princess Diana confronted Camilla Parker Bowles at a party in 1989

The princess described their meeting at a party in 1989 in the second set of tapes aired by US network NBC.

She said: "I was terrified of her. I said, 'I know what's going on between you and Charles and I want you to know that. Don't treat me like an idiot.'"

Andrew Morton used the tapes for his book Diana: Her True Story.

Growing depression

Last week, NBC aired parts of the secretly recorded tapes - made at Kensington Palace in the early 1990s - on which the princess blamed the affair for worsening her growing depression which led to her attempting to kill herself.

I said I want my husband Diana, Princess of Wales

In Thursday night's programme, she described the confrontation with Mrs Parker Bowles, which occurred at a birthday party for Mrs Parker Bowles' sister.

The princess said: "The voice inside me had said 'just go for it'.

"I was terrified of her. I said, 'I know what's going on between you and Charles and I just want you to know that'."

She said Mrs Parker Bowles told her: "You've got everything you ever wanted. You've got all the men in the world falling in love with you and you've got two beautiful children, what more do you want?".

Mock interview

"So I said, 'I want my husband'," Diana said.

"And I said to Camilla, 'I'm sorry I'm in the way... and it must be hell for both of you. But I do know what's going on. Don't treat me like an idiot'."

The programme also showed film taken by a voice coach when the princess was training for a new, more public, role as a single woman.

In a mock interview, she is asked what she would do if she was not the Princess of Wales.

The princess replied: "I would like to have a role which brought me into contact with every day life and the man on the street - does that sound condescending?"