The Metropolitan Police say officers are "scoping" the information relating to the death of Diana and her lover Dodi Al-Fayed in a Paris underpass in 1997, and "assessing its relevance and credibility".
The police have refused to provide details of the information received but it is believed to contain allegations the pair were murdered by a member of the British military.
The Metropolitan Police said it was "not a re-investigation" into the deaths of the couple in a car crash on August 31 1997.
Reportedly, the allegation was made by the former parents-in-law of an ex-soldier based on information that the former serviceman had talked about in the past.
It is suggested the allegations include a reference to the SAS and to the Princess's "secret diary".
The information is said to have been passed to the Met through the Royal Military Police.
A 2008 inquest found they were unlawfully killed partly 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 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".
But according to some reports, the information is believed to have come from British Army personnel.
Scotland Yard said the assessment did not come under Operation Paget - the police investigation into allegations that Diana and her boyfriend Dodi were murdered, a theory endorsed at the time by Dodi's father Mohamed Al Fayed.
A spokesman for Al Fayed said: "He trusts that their investigation will be thorough and awaits the outcome with interest."
Diana, Dodi and chauffeur Henri Paul died after their Mercedes crashed in the Pont de l'Alma tunnel after leaving the Ritz Hotel, owned by Mohammed Al-Fayed in the early hours of the morning.
The inquest hearing into the deaths which concluded on April 7, 2008, lasted more than 90 days with evidence from around 250 witnesses.
After the hearing it was announced its cost had reached £4.5m, with a further £8m spent on the Met investigation.
Graeme Pearson, a Scottish Labour MSP, shadow justice secretary, member of the Scottish Parliament's Justice Committee and the former director general of the Scottish Crime and Drug Enforcement Agency, said officers were likely to assess the motives of the source of the information and look at why the information was not available at an earlier stage.
He said: "A very basic effort will be initiated to judge the sense or otherwise of taking further a new stage in what otherwise has been a comprehensive enquiry, conducted in the search light of media interest, looking into every aspect of the circumstances leading up to and beyond the events resulting in the deaths. It is difficult to believe that more than £12m of public money spent thus far has failed to answer most of the questions. Many families would have wished their experience of deaths affecting their loved ones could have attracted a similar level of attention.
"Why announce now the work unless a media outlet was pursuing the story? Who caused this story to launch at this time near the anniversary date ignoring the detrimental impact on the feelings and emotions of those close to the deceased in this case?"
The Specialist Crime and Operations Command which will carry out the probe is the serious crime wing of the Met and is headed by Assistant Commissioner Mark Rowley. It is currently investigating whether large severance payouts to BBC executives broke the law. The fatal Paris crash happened after the couple were pursued by paparazzi. Al-Fayed's bodyguard, Trevor Rees-Jones, was the only survivor.
Former Met Police Commissioner Lord Stevens's Operation Paget investigation was launched in 2004 at the request of Michael Burgess, the Royal Coroner, who was then overseeing the future Diana inquest.
The former top policeman published his report in 2006, rejecting the murder claims voiced by some. Lord Stevens's investigation found that Diana was not murdered and she was not pregnant, nor engaged to boyfriend Dodi.
Operation Paget concluded, just like the French investigation, that Paul was drunk and driving at excessive speed. The black type S280 Mercedes was being driven at around 61 to 63mph - twice the speed limit for that section of road.
The former Harrods boss has long accused Met Police chiefs of deliberately withholding evidence from the French investigation.
In 2009 a French inquiry into the investigation into Diana's death heavily criticised the French authorities and the French state was ordered to pay almost £5,000 in compensation to Mr Al Fayed.
The Court of Grand Instance in Paris decided the inquiry had been seriously mishandled, but said the errors did not affect its overall conclusion that the deaths were the result of an accident.
Investigators had bungled the autopsies and mishandled blood tests causing delays of almost two years in the case.
There were also hitches in establishing whether Paul was drunk at the wheel.