PARIS (REUTERS) - Mourners marked the 25th anniversary of Princess Diana's death in Paris on Wednesday (Aug 31), laying flowers and leaving messages on the bridge above the underpass where she was killed in a car crash.

Blooms and pictures of Princess Diana adorned the gold-leaf covered Flame of Liberty, a replica of the torch of the Statue of Liberty at the Pont de L'Alma's northern end that has become her unofficial memorial in the French capital.

The Princess was just 36 when the limousine carrying her and her lover Dodi al-Fayed crashed in the tunnel below the bridge as it sped away from photographers who were chasing it on motorbikes.

"Deja 25 ans (25 years already)," read one of the cards left on the memorial, where a trickle of locals and tourists - surrounded by media camera crews - came to pay their respects, leave flowers and take pictures.

"Forever in our hearts," read another with a Diana picture left by someone who identified herself as Monique from Luxembourg.

Millions globally mourned the "People's Princess", as then British Prime Minister Tony Blair described Princess Diana, in 1997.

She was one of the world's most recognised and photographed women and a high-profile supporter of humanitarian causes, including children's charities and land mine clearance, when she died.

The mother of Princes William and Harry, her death plunged the monarchy into crisis, coming after the disintegration of her marriage to heir to the throne Prince Charles with its revelations of feuding, adultery and the misery she had felt in her royal role.

The continued fascination with Princess Diana's life was illustrated on Saturday (Aug 27) when a black Ford Escort that she drove in the 1980s was sold at auction in Britain for £724,500 (S$1.18 million).