Hollande Says World Must Act over Syria Weapons Proof

French President Francois Hollande said Wednesday that the world was obligated to act in response to concrete evidence of the deadly nerve agent sarin being used in Syria.

"We have provided the elements of proof that now obligate the international community to act," Hollande told reporters in Paris a day after France revealed that it had firm evidence sarin had been used by the Syrian regime in at least one case.

Britain has also said it has evidence of sarin use, but has said it will wait for independent verification by the U.N. before drawing any conclusions about what, if any, action to take.

The United States meanwhile has been emphasizing hopes for progress through negotiations involving Russia aimed at organizing a peace conference in Geneva.