The Princess of Wales died in car accident along with her companion Dodi al Fayed and their chauffeur Henri Paul in August 1997 while they were being chased by paparazzi in Paris.
The UK's Sky News is reporting that the information includes the allegation that Diana, al Fayed and their driver were killed by a member of the British military.
"The information we're told was passed to Scotland Yard quite recently," reports Sky's Crime Correspondent Martin Brunt.
"It also includes, we understand, references to something known as Diana's diary."
Scotland Yard stressed that it was not reopening an investigation into the accident.
A 2008 inquest found that Diana and al Fayed had been unlawfully killed as the result of "grossly negligent driving of the following vehicles and of the Mercedes."
Mohammed al Fayed, Dodi's father, has repeatedly claimed the couple were murdered.
The Egyptian-born Mohammed, who owned the London department store Harrods, claimed that the royal family had Diana killed to prevent her from marrying a Muslim and giving birth to a Muslim half brother to a future king, Prince William.
A report from Operation Paget, the investigation into conspiracy theories over the accident, said it had found no evidence of murder.
Diana, the mother of Princes William and Harry, was just 36 when she died.
The anniversary of the accident is on August 31.