France is testing samples of suspected chemical weapon elements used against Syrian rebel fighters and smuggled out by reporters from Le Monde newspaper and will divulge the results in the next few days, a senior French official said on Monday.
The official also said Paris recently carried out its own tests on other samples it had obtained that had indicated the use of battlefield gas.
"Samples were handed to our intelligence services by the Le Monde journalists," the senior official said on condition of anonymity. "Tests will be done on these samples and the results made known in the coming days."
The newspaper, in a report issued on its website earlier on Monday, said one of its photographers had suffered blurred vision and respiratory difficulties for four days after an attack on April 13 on the Jobar front, just inside central Damascus.
President Bashar al-Assad's government and the rebels fighting to oust him have accused each other of using chemical weapons. U.N. investigators have been ready for weeks, but diplomatic wrangling and safety concerns have delayed their entry into Syria.
Undercover in and around the Damascus area for two months alongside Syrian rebels, a Le Monde reporter and photographer said they witnessed battlefield chemical attacks and also talked to doctors and other witnesses about their aftermath.
The French official, who was speaking after talks among U.S. Secretary of State John Kerry, Russian Foreign Minister Sergei Lavrov and French Foreign Minister Laurent Fabius in Paris, said the three ministers had agreed that any use of chemical weapons would be a game changer.
"The question of chemical weapons can create a different situation because the divisions on that are not the same as on the Syrian conflict," the official said.
"If we have enough elements that converge to say that chemical weapons were used, then we will have to take a decision with our partners to examine the possible consequences."
Syria, which is not a member of the anti-chemical weapons convention, is believed to have one of the world's last remaining stockpiles of undeclared chemical arms.
The French official said the talks among the foreign ministers had been useful, but that reaching agreement on holding Syrian peace talks remained "very difficult" and that a great deal still had to be resolved if they were to be held in mid-June.