Damian Dalby told an inquest into Diana's death that he and his brother rushed over to the wreckage of the princess' Mercedes after it crashed in the Pont d'Alma tunnel on Aug. 31, 1997.
Dalby, who was a volunteer French firefighter at the time, told the inquest by video-link from Paris that the car was surrounded by photographers.
"The car's rear, right-hand side door was open, and a photographer was close by, but he did not stop me from doing my assistance job," Dalby said.
Ian Burnett, lead lawyer for the inquest, asked Dalby: "Was it right the lady in the car was trying to speak?"
"Yes, she was saying 'Oh my God, Oh my God,"' Dalby said.
Dalby said police arrived on the scene and moved the photographers away.
The inquest is examining the deaths of Diana and her companion Dodi Fayed in Paris, where the couple had been pursued by paparazzi. Witnesses have testified that photographers were among the first to reach the scene of the crash.
The jury heard Thursday from a statement given by Dalby's brother, Sebastien Pennequin, shortly after the crash. Pennequin said he tried to help police move photographers away.
"They continued taking photographs, it was then I spoke to them telling them to stop," the statement said. "'The people must know that Princess Diana is alive,' one of them said."
The inquest _ required by British law when someone dies unexpectedly, violently or of unknown causes _ had been delayed for 10 years because of the two exhaustive investigations by French and British police.
Both concluded that the couple's driver, Henri Paul, was drunk, driving too fast and that the deaths were an accident. Paul also died.
Fayed's father contends that the couple were the targets of a plot orchestrated by Prince Philip, the husband of Queen Elizabeth II.
Earlier Thursday, a French man who claims Diana died in a trap set by photographers faced skeptical lawyers.
Jacques Morel alleges that the late French photographer James Andanson organized a plan to stop the car carrying Diana and Fayed in the tunnel so paparazzi could take photos and get interviews. He says he has written a book on the subject, so far unpublished.
Morel, who began testifying Wednesday, said he saw a line of 10 to 12 photographers and a man with a video camera just inside the tunnel before the crash on Aug. 31, 1997. No other witness has claimed to see photographers waiting in the tunnel, though several have said photographers were quickly at the scene.
Morel claimed he had seen secret papers supporting his contention, but Michael Mansfield, a lawyer for Fayed's father, Mohamed al Fayed, questioned whether such a file existed.
"How would you like to bet?" said Morel, who testified via video link from Paris. "I can bet with you 1 million U.S. dollars, and if you bet with me, I can send you the file within 24 hours."
Morel claimed he had given a copy of the file to Fayed's legal team, which Mansfield denied.
Mohamed al Fayed has alleged that Andanson, who died in 2000, was involved in a plot to kill his son and the princess, and that he was the driver of a white Fiat Uno which collided with the couple's car near the tunnel.
That car has never been traced.