Story highlights Ministry of Defence says claim is for civilian police to deal with

But police seem to be knocking down claim that commandos were involved in Diana's death

Allegation emerged amid collapse of soldier's marriage

London police stress they are not re-investigating, merely assessing credibility

A newly revealed claim of conspiracy in the death of Princess Diana has royal watchers buzzing once again, nearly 16 years after the woman who would now be a royal grandmother died in a Paris car crash.

But British police seem to be knocking down the claim -- that the British military was involved in the deaths of Diana, her boyfriend and their driver in August 1997.

"This is not a re-investigation," London Metropolitan Police tersely stressed, in a statement that revealed none of what it had been told.

The latest claim appears to have been sent first to military authorities and then to London police by the parents-in-law of a British special forces sniper after his marriage had fallen apart, according to an article on the website of the Sunday People newspaper. It did not offer a source for its reporting.

Photos: Princess Diana: Her life and legacy Photos: Princess Diana: Her life and legacy Princess Diana remains a beloved figure more than 20 years after her untimely death. See more photos of the British icon and the legacy she left behind. Hide Caption 1 of 47 Photos: Princess Diana: Her life and legacy Diana, seen here on her first birthday, was born Diana Frances Spencer on July 1, 1961. She was born into a noble family in Sandringham, England. Her father, John, was Viscount Althorp before becoming the 8th Earl Spencer in 1975. Hide Caption 2 of 47 Photos: Princess Diana: Her life and legacy Diana circa 1965. Growing up, she attended private schools in England and Switzerland. Hide Caption 3 of 47 Photos: Princess Diana: Her life and legacy Diana poses with her brother, Charles, in 1968. She also had two sisters, Sarah and Jane. Hide Caption 4 of 47 Photos: Princess Diana: Her life and legacy Diana, far right, is photographed with her father, John, and her three siblings circa 1970. Sarah is on the far left and Jane is next to Diana. When Diana was 7 years old, her parents divorced and her father was given custody of the children. Hide Caption 5 of 47 Photos: Princess Diana: Her life and legacy A teenage Diana receives a "kiss" from her pony, Scuffle, in 1974. A year later, she became Lady Diana after her grandfather died and her father became the 8th Earl Spencer. Hide Caption 6 of 47 Photos: Princess Diana: Her life and legacy After finishing school, Diana worked various jobs, including cook, nanny and kindergarten teacher. Here she is in 1980 with two children she looked after as a nanny. Hide Caption 7 of 47 Photos: Princess Diana: Her life and legacy Diana and Camilla Parker-Bowles visit the Ludlow racecourse in October 1980, where Prince Charles was competing as a jockey. Diana and Charles would be engaged just a few months later. Prince Charles admitted in 1994 to a relationship with Parker-Bowles while still married to Diana; Charles and Camilla wed in 2005. Hide Caption 8 of 47 Photos: Princess Diana: Her life and legacy Diana looks startled after stalling her new car outside her London apartment in November 1980. Hide Caption 9 of 47 Photos: Princess Diana: Her life and legacy Diana is surrounded by photographers shortly before it was announced that she was engaged to Prince Charles. Hide Caption 10 of 47 Photos: Princess Diana: Her life and legacy Diana and Charles pose at Buckingham Palace after the announcement of their engagement on February 24, 1981. Hide Caption 11 of 47 Photos: Princess Diana: Her life and legacy Diana and Charles arrive at Goldsmith Hall in London for a charity recital in March 1981. Hide Caption 12 of 47 Photos: Princess Diana: Her life and legacy The couple poses with Charles' mother, Queen Elizabeth II, in March 1981. Hide Caption 13 of 47 Photos: Princess Diana: Her life and legacy The royal wedding was held July 29, 1981, at St. Paul's Cathedral in London. It was estimated that more than 700 million people watched the ceremony on television. Hide Caption 14 of 47 Photos: Princess Diana: Her life and legacy Charles and Diana kiss on the Buckingham Palace balcony after being married. Hide Caption 15 of 47 Photos: Princess Diana: Her life and legacy During their honeymoon, Charles and Diana leave Gibraltar on the royal yacht Britannia. Hide Caption 16 of 47 Photos: Princess Diana: Her life and legacy The couple spends part of their honeymoon in Scotland. Hide Caption 17 of 47 Photos: Princess Diana: Her life and legacy Charles and Diana attend the Grand National horse race in April 1982. Hide Caption 18 of 47 Photos: Princess Diana: Her life and legacy In June 1982, Diana gave birth to her first child, William. Hide Caption 19 of 47 Photos: Princess Diana: Her life and legacy Diana greets a child while visiting Wrexham, Wales, in November 1982. Hide Caption 20 of 47 Photos: Princess Diana: Her life and legacy Charles, William and Diana pose for a photo at Kensington Palace in February 1983. Hide Caption 21 of 47 Photos: Princess Diana: Her life and legacy Diana gave birth to a second son, Harry, in September 1984. Hide Caption 22 of 47 Photos: Princess Diana: Her life and legacy Charles kisses his wife after a polo match in Cirencester, England, in June 1985. Hide Caption 23 of 47 Photos: Princess Diana: Her life and legacy Diana watches her boys play at the piano in Kensington Palace in October 1985. Hide Caption 24 of 47 Photos: Princess Diana: Her life and legacy Diana helps William with a puzzle in October 1985. Hide Caption 25 of 47 Photos: Princess Diana: Her life and legacy Diana attends a polo match that her husband played in Palm Beach, Florida, in November 1985. Hide Caption 26 of 47 Photos: Princess Diana: Her life and legacy Diana dances with actor John Travolta at the White House in November 1985. Dancing behind Travolta are US President Ronald Reagan and first lady Nancy Reagan. A few years ago, Diana's blue velvet dress -- nicknamed the "Travolta dress" -- was auctioned for 240,000 British pounds ($362,424 US). Hide Caption 27 of 47 Photos: Princess Diana: Her life and legacy Diana holds up Harry in the garden of Highgrove House, a royal residence in Gloucestershire, England, in July 1986. Hide Caption 28 of 47 Photos: Princess Diana: Her life and legacy William rides a miniature pony at Highgrove House. Hide Caption 29 of 47 Photos: Princess Diana: Her life and legacy Prince Harry shows a bit of his personality on the Buckingham Palace balcony in June 1988. Hide Caption 30 of 47 Photos: Princess Diana: Her life and legacy Diana and her two boys walk outside the Wetherby School in London in April 1990. Hide Caption 31 of 47 Photos: Princess Diana: Her life and legacy Diana and her sons go skiing in Lech, Austria, in April 1991. Hide Caption 32 of 47 Photos: Princess Diana: Her life and legacy Diana and Charles sit together during a royal tour of Toronto in October 1991. Hide Caption 33 of 47 Photos: Princess Diana: Her life and legacy Diana visits Egypt in May 1992. Hide Caption 34 of 47 Photos: Princess Diana: Her life and legacy Charles and Diana attend a memorial service during a tour of South Korea in November 1992. A month later, it was announced that they had formally separated. Hide Caption 35 of 47 Photos: Princess Diana: Her life and legacy Diana and her sons visit Thorpe Park, a theme park in Surrey, England, in April 1993. Hide Caption 36 of 47 Photos: Princess Diana: Her life and legacy Diana arrives at the Serpentine Gallery in London in June 1994. Hide Caption 37 of 47 Photos: Princess Diana: Her life and legacy A police officer holds back a photographer as Diana walks by in July 1996. It had just been announced that Diana and Charles had divorced. Hide Caption 38 of 47 Photos: Princess Diana: Her life and legacy Diana talks to amputees in Angola, where she traveled in January 1997 to bring attention to the anti-land mine campaign of the International Red Cross. Sitting on her lap is Sandra Thijica, a 13-year-old who lost her left leg to a land mine. Hide Caption 39 of 47 Photos: Princess Diana: Her life and legacy Diana wears protective gear as she visits minefields in Angola in January 1997. Hide Caption 40 of 47 Photos: Princess Diana: Her life and legacy Diana visits Cape Town, South Africa, and meets with South African President Nelson Mandela in March 1997. Hide Caption 41 of 47 Photos: Princess Diana: Her life and legacy Diana holds hands with Mother Teresa after they met in New York in June 1997. Hide Caption 42 of 47 Photos: Princess Diana: Her life and legacy This photo, taken from surveillance video, shows Diana arriving at the Ritz Hotel in Paris on August 30, 1997. It is one of the last photos of her alive. Hide Caption 43 of 47 Photos: Princess Diana: Her life and legacy Diana is seen in a Ritz Hotel elevator with her boyfriend, Dodi Fayed. After leaving the hotel, the couple was killed in a high-speed car crash in the Pont de l'Alma tunnel in Paris. Hide Caption 44 of 47 Photos: Princess Diana: Her life and legacy Wreckage is lifted away after the car Diana was in crashed into a pillar on August 31, 1997. Fayed and driver Henri Paul died at the scene. Diana died at a Paris hospital a few hours later. A French investigation concluded that Paul was legally drunk at the time and responsible for the accident. In 2008, a British coroner's jury found that Diana and Fayed were unlawfully killed because of the actions of Paul and pursuing paparazzi. Hide Caption 45 of 47 Photos: Princess Diana: Her life and legacy On the eve of Diana's funeral, the Queen and Prince Philip look at floral tributes left outside Buckingham Palace. More than 1 million bouquets of flowers were left at Kensington Palace, Buckingham Palace and St. James's Palace in the wake of Diana's death. Hide Caption 46 of 47 Photos: Princess Diana: Her life and legacy Diana's coffin is carried into London's Westminster Cathedral in September 1997. Watching at the bottom, from left, is Prince Charles, Prince Harry, Charles Spencer, Prince William and Prince Philip. Hide Caption 47 of 47

JUST WATCHED New info on Diana's death surfaces Replay More Videos ... MUST WATCH New info on Diana's death surfaces 02:02

JUST WATCHED Police: Diana death probe not re-opened Replay More Videos ... MUST WATCH Police: Diana death probe not re-opened 01:25

JUST WATCHED New Princess Diana investigation Replay More Videos ... MUST WATCH New Princess Diana investigation 02:02

Sunday People said it had seen a seven-page handwritten letter by the in-laws alleging that the soldier, whom the newspaper did not name, had boasted to his wife that the elite British Special Air Service commando unit was behind the deaths.

The UK Ministry of Defence told CNN only that "this is for Metropolitan Police to investigate."

Military authorities have been aware of the claim since the 2011 court-martial of the soldier's former roommate on weapons charges, Sunday People reported. The unnamed soldier mentioned in the letter was a witness in that case, according to the newspaper.

Neither the Sunday People piece nor an earlier version carried by Press Association offered details of the claimed involvement by soldiers in the deaths.

Diana, 36, and Dodi Fayed, her 42-year-old boyfriend, died when the Mercedes-Benz they were traveling in hit a pillar in the Pont de l'Alma tunnel in Paris in August 1997.

They were being followed at the time by the paparazzi after leaving the Ritz Hotel. Their driver, Henri Paul, was also killed. Investigators concluded that Paul was drunk and driving at high speed. Bodyguard Trevor Rees-Jones was the sole survivor.

A British coroner's inquest in 2007 concluded that the deaths were the result of "grossly negligent driving of the following vehicles and of the Mercedes." The inquest found no evidence of murder. A London police spokesman said no new information had been examined since this inquest.

Yet the deaths have always been paired with conspiracy theories accusing British and French intelligence services and members of British royalty of orchestrating Diana's death.

The Daily Mirror reported in 2003 that the Princess of Wales wrote to her former butler Paul Burrell 10 months before she died, saying her life was at its "most dangerous" phase and warning of a plot to tamper with the brakes of her car.

After their deaths, Mohamed al Fayed, Dodi's father, said the couple were planning to announce their engagement and publicly accused Prince Philip, Diana's former father-in-law, of orchestrating the couple's murders. He testified at the 2007 inquest.

A spokesman for al Fayed said Sunday he had no comment at this time but trusts the police will do a thorough investigation.

Diana remains wildly popular in death, and news of the new claim sparked an immediate surge in discussion of her death on news sites and social media.

But many seemed skeptical.

"Is it just me or does it (seem) like a Princess Diana conspiracy hits around this time of year, every year?," Twitter user DMR09 posted.

The rumors come to light weeks before the 16th anniversary of Diana's death, and a little more than a month before the British premier of "Diana," a new movie about the former princess's life.

It's unclear whether these allegations will make it any further than previous claims have. London police seem unlikely to make any big announcements, based on the closing line of their statement.

"Not Prepared to Discuss Further," Scotland Yard said in the statement.