France says it is "certain" that Syrian government has used sarin gas BEIRUT - The French government said Tuesday that it has confirmed the use of sarin gas by the Syrian government, and a U.N. panel reported that it has "reasonable grounds" to believe chemical weapons have been used in the country's civil war, deepening international suspicions that the red line set by President Obama has been breached. France "now is certain that sarin gas was used in Syria multiple times and in a localized way" after tests carried out by a French laboratory on samples taken from victims proved the presence of the nerve gas, according to a statement issued by French Foreign Minister Laurent Fabius. Liz Sly Separately, U.N. cites "reasonable grounds" to believe Assad's troops have deployed chemical weapons. Colum Lynch On a range of issues, Russia has used its power in the Security Council to act as a bureaucratic spoiler. The report by the United Nations" independent commission of inquiry on Syria said the panel had not been able to ascertain which chemicals had been used, how they were delivered or by whom, because it did not have access to samples taken directly from victims. But it said it had "reasonable grounds to believe that limited quantities of toxic chemicals were used" on at least four occasions between March and April this year. Other reported instances are still being investigated, and it is of the "utmost import" that Syria grant access to the U.N. team of experts tasked with probing the allegations, it said. Fabius said his government is confident that the regime of Syrian President Bashar al-Assad was responsible for at least one of the two instances in which it had confirmed the use of the gas. "In the second case, there is no doubt that it is the regime and its accomplices," Fabius told the France 2 television station in a separate interview. We have integrally traced the chain, from the attack, to the moment people were killed, to when the samples were taken and analyzed. His comments followed an eyewitness account by two reporters with France's Le Monde newspaper describing how canisters containing small quantities of what appeared to be a nerve agent had repeatedly been fired at rebel positions during their two-week stay with opposition fighters in the eastern suburbs of Damascus, a hotly contested battleground where the government has made significant advances in recent weeks. The reporters said they had taken samples from the victims for analysis in France, and Fabius said those samples were one of two sources for France's conclusion that sarin has been used. "All options are on the table," he said when asked what France's response might be. That means we could decide not to intervene, or we could decide to intervene, including militarily, where the gas is produced or stored. Obama warned last year that chemical weapons represented a "red line" that would trigger U.S. intervention, but U.S. officials have repeatedly stressed that they do not have convincing evidence that banned chemicals have been used. The latest reports are likely to compound pressure on the administration to do more to influence the outcome of the conflict, which the U.N. report said continues to escalate to "new levels of brutality." The report painted a bleak picture of an increasingly complex and cruel war in which sectarian sentiments are deepening, atrocities are becoming more common and the threat of a regionwide conflict is growing.