Police investigating credibility of claims, including that SAS was behind death.
Scotland Yard has launched an investigation into new claims that Diana, Princess of Wales was murdered by a member of the British military.
It said that it had asked specialist detectives to examine new allegations and evidence passed to it "recently". The move was approved by Sir Bernard Hogan-Howe, its most senior officer.
The claims were given to the force by the Royal Military Police, after surfacing during the trial of Sergeant Danny Nightingale, the SAS sniper convicted of illegal weapons possession.
The dossier is said to include a claim that the SAS "was behind Princess Diana's death". Scotland Yard declined to confirm the content or origin of the material.
Officers from the specialist crime and operations command will carry out a "scoping" exercise to assess if a full-scale investigation is justified into whether the Princess, her boyfriend Dodi Fayed and driver Henri Paul were murdered.
The disclosure comes in spite of the inquest into the death of the Princess and Fayed dismissing any claims of murder made by Mohammed Fayed, Dodi's father, and conspiracy theorists.
Since then murder claims have continued to be made but have never been looked into by British police - making yesterday's move unprecedented.
The claims come from the estranged parents-in-law of "Soldier N", an SAS soldier who was a key witness in the successful prosecution of Nightingale. He was himself convicted of illegal weapons possession. His estranged wife's parents wrote to the SAS's commanding officer claiming the soldier had told his wife that the unit had "arranged" the Princess's death and that this had been "covered up".
The source of the claims will inevitably raise questions over their credibility, and why Scotland Yard acted.
Scotland Yard emphasised that it was not reopening the previous investigation into the deaths, Operation Paget, and highlighted the verdict of the inquest held after that inquiry was completed.
Officers will have to assess whether the information has not been investigated previously and can potentially shed new light on the deaths.
The development comes ahead of next week's 16th anniversary of the Princess' death as a result of injuries she suffered when the Mercedes in which she was travelling crashed in a tunnel in Paris.
A spokesman said: "The Metropolitan Police Service is scoping information that has recently been received in relation to the deaths and assessing its relevance and credibility.
"The assessment will be carried out by officers from the specialist crime and operations command. This is not a reinvestigation and does not come under Operation Paget. On April 7, 2008, the [inquest] jury concluded their verdict as 'unlawful killing, grossly negligent driving of the following vehicles and of the Mercedes'."
Detectives are understood to have contacted the former soldier's estranged wife. A royal spokesman said there would be no comment from the Duke of Cambridge, Prince Harry or Clarence House. A spokesman for Fayed said he would be "interested in seeing the outcome".
The jury at the inquest returned a majority verdict in April 2008, which indicated that paparazzi photographers who pursued the Princess were to blame for her "unlawful killing".
Paul was also culpable for her death due to his "gross negligence" in driving while three times over the drink-drive limit, the jury found.
An earlier French police investigation cleared the photographers of being directly linked to the tragedy.