Simmons said Diana had reason to suspect that the Secret Intelligence Service was out to get her, and described "derogatory" letters the princess received from Prince Philip after her split from his son, Prince Charles, The Telegraph and The Daily Mirror reported.

Simmons -- described as an "energy healer" -- has written several books about Diana. She told reporters she began seeing the princess several times a week for healing sessions in 1993.

Simmons claimed that she listened to a threatening phone call in February 2007 that Diana received from someone who she thought was conservative Member of Parliament Nicholas Soames, regarding her commitment to ridding the world of land mines.

Simmons said Diana had also mentioned letters of a "cruel" nature that she received from Prince Philip in 1994 and 1995, which made Diana "red in the face" and changed the way she viewed her relationship with her father-in-law.