"What we have been told is that this evidence that the Americans, the British, the French say they have is going to be shared with us. It hasn't been until now," he said. "And we will be very, very, very interested in hearing from them what this evidence they have is."
Syria has one of the world's largest stockpiles of chemical charges, but denies the charges. U.S. leaders have not presented their proof, and U.N. inspectors have yet to comment on the allegations.
Brahimi called the civil war — which has killed more than 100,000, forced about 2 million refugees from their homes and displaced millions of others — the most serious crisis facing the international community.
But he said that any U.S.-led military action must first gain approval from the 15-nation Security Council, whose five permanent members — Britain, China, France, Russia and the United States — each have veto power. The United States has been laying the groundwork for a possible strike on Syria, but U.N. Secretary-General Ban Ki-moon has urged nations to allow more time for diplomacy.
Britain says it will seek a measure "authorizing necessary measures to protect civilians" in Syria. They want it drafted under Chapter 7 of the U.N. Charter, which is militarily enforceable, when it is a political resolution that doesn't mandate any specific actions.
"International law says that military action must be taken after a decision by the Security Council," Brahimi said. "I must say that I do know that President Obama and the American administration are not known to be trigger-happy.-What they will decide, I don't know. But certainly international law is very clear: the Security Council has to be brought in."