French investigators began Saturday trying to identify the bodies of 43 victims of a coach crash blaze near Bordeaux, while combing the wreckage for answers to what caused the country's worst road accident in three decades.

Experts from a police victim identification unit set up a tented centre overnight with equipment and tables for carrying out examinations following Friday's collision, a local police chief told AFP.

In the worst accident on French roads in 33 years, a coach carrying members of a pensioners' club on an excursion collided with a lorry and burst into flames near the village of Puisseguin, among the vineyards of the Saint-Emilion area.

"They will begin working from sunrise, body by body, in a very methodic way" using DNA and dental remains to try to put names to the bodies, said Ghislain Rety, police colonel in the Gironde region.

Many of the victims were thought to have died in the fire, according to emergency workers and local authorities, and officials say formally identifying them all could take up to three weeks.

One of the survivors told Saturday of the desperate efforts to rescue people from the burning coach.

"The fire broke out straight away -- it was like lightning," 73-year-old retired carpenter Jean-Claude Leonardet, who managed to escape the burning vehicle, told Le Parisien newspaper.

"We went back to pull two people who were trapped on the stairs and couldn't get out," he said.

"We couldn't go back there -- the fire and the smoke were overwhelming."



'White roses for the dead'

Investigators will study the lorry's tachograph, a sort of black box that records the vehicle's speed and journey time, for clues but Rety said it was in a "very, very damaged state".

"It's too early to say if it will be usable," Rety warned.

The wreckage of the vehicles will also be examined to try to establish the circumstances of the crash.

The specialists' work is similar to that done to identify the remains of air crash victims and some of the investigators worked on the Germanwings disaster that killed 150 people in the Alps earlier this year.

They must also still determine exactly how many passengers were on board the coach as there is no official list. "The only list was in the coach, it's burnt," the police chief said.

Puisseguin and nearby small villages, where most of the victims came from, were in mourning Saturday. At the mortuary, in the absence of bodies 43 white roses were laid out in symbolic tribute to the victims.

The pensioners had been heading south to the nearby region of Landes to visit an outlet and museum specialising in Bayonne ham, a local delicacy.

Police on Friday said the lorry driver was also killed along with his three-year-old son who was sitting beside him.

Eight people, including the coach driver, managed to escape the burning wreckage.

Formal identification of the victims could take up to three weeks, an expert from the police's victim identification unit said Friday.

The crash is the deadliest in France since August 1982, when 53 people including 44 children were killed in a motorway pile-up in the eastern Burgundy region.