The Metropolitan Police is assessing new information it has recently received about the deaths of Princess Diana and Dodi Al Fayed in 1997.
Scotland Yard says it is “scoping” the details and “assessing its relevance and credibility”.
It said it was “not a re-investigation” into the deaths of the couple in a Paris car crash on 31 August 1997.
An inquest in 2008 found they were unlawfully killed due to the “gross negligence” of their driver.
In a statement, the Metropolitan Police said the assessment would be carried out by officers from the Specialist Crime and Operations Command.
It added that the deaths “were thoroughly investigated, and examined” by the inquest held at the Royal Courts of Justice in London.
A Met Police spokesman said that the force would “not discuss the source of the information” it was assessing.
Paparazzi on motorbikes
Scotland Yard added that the assessment did not come under Operation Paget – the police investigation into allegations that Diana and her boyfriend Dodi were murdered.
It was a theory endorsed at the time by Dodi’s father Mohamed Al Fayed, then owner of Harrods.
In December 2006, the report into Operation Paget said it had found no evidence that the couple were murdered.
Princess Diana, the former wife of the the Prince of Wales and mother of Princes William and Harry, was 36 at the time of her death.
She and Dodi died when their driver Henri Paul crashed a hired Mercedes into a pillar in the Pont de l’Alma tunnel.
The crash happened after the couple left the Ritz Hotel, pursued by paparazzi on motorbikes. Dodi’s bodyguard Trevor Rees-Jones was the only survivor.
At the inquest, the jury found that paparazzi, Mr Paul’s drink-driving and a lack of seatbelts contributed to their deaths.
After the hearing it was announced that the cost of the coroner’s inquest reached £4.5m, with a further £8m spent on the Metropolitan Police investigation.
A royal spokeswoman said there would be no comment on the matter from Prince William or Prince Harry, or from Clarence House.