The Metropolitan Police has said there is no 'credible evidence' to suggest the SAS was involved in the deaths of Diana, Princess of Wales and Dodi Al Fayed in a Paris car crash.
Earlier this year Scotland Yard began a so-called 'scoping' exercise to assess the credibility of allegations that the couple were murdered by a member of British special forces.
The investigation began in August after claims, thought to have been made by the former parents-in-law of an ex-soldier and based on information that he had talked about in the past, came to light.
The central allegation was that members or former members of the SAS were involved in the circumstances leading to the deaths of the couple.
The 'scoping' exercise was carried out in order to assess the "relevance and credibility" of the information provided, and to decide whether it was sufficient to warrant a reopening of the criminal investigation.
Diana, Princess of Wales, Dodi al Fayed and their chauffeur Henri Paul died as a result of injuries sustained in a car crash in the Pont de l'Alma road tunnel in Paris on August 31, 1997.
Initially, blame for the accident was ascribed to the paparazzi photographers who were following the vehicle. However, a French judicial investigation later found that the crash was caused by Mr Paul, who had lost control of the vehicle while allegedly drunk.
The investigation claimed photographers were not near the hired black 1994 Mercedes-Benz S280 vehicle when it crashed.
The British hearing into the deaths of Diana and Dodi lasted more than 90 days, with evidence from around 250 witnesses.
The inquests concluded on April 7 2008, with a jury returning a verdict that the "People's Princess" and her boyfriend were unlawfully killed.
In a statement the Metropolitan Police said today: "This assessment included taking statements from a number of individuals and reviewing records. As part of the scoping officers were given unprecedented access to Special Forces Directorate records.
"Every reasonable line of inquiry was objectively pursued in order to fully evaluate any potential evidence.
"The final conclusion is that, whilst there is a possibility the alleged comments in relation to the SAS's involvement in the deaths may have been made, there is no credible evidence to support a theory that such claims had any basis in fact.
"Therefore the MPS are satisfied there is no evidential basis upon which to open any criminal investigation or to refer the matter back to HM Coroner."
Mohamed al Fayed, Dodi's father, said he was "disappointed" by the outcome and will continue his fight "to establish the truth that they were murdered", his solicitor, Simon McKay, said.
Mr McKay branded the "so-called scoping exercise" "the latest whitewash in a 16-year cover-up".
He added: "The Met should never have been given charge of the case as they had every incentive to return the result we now see. To have done anything else would have called into serious question their own Paget Report of 2007."
"The case of Soldier N should have been rigorously investigated by the Royal Military Police."
Mr McKay commented that the Paget Report "said the deaths were accidental, a judgment overruled by the jury at the inquests that said that Dodi and Diana had been unlawfully killed."
"Mr al Fayed will continue his fight to establish the truth that they were murdered and is convinced he will succeed in doing so."
Additional reporting by the Press Association.