U.N. Secretary-General Ban Ki-moon is urging world powers to hold off on any military strike against Syria until a U.N. chemical weapons team completes its work in that country.

Spokesman Farhan Haq says the inspectors will leave Syria on Saturday. He says some of them will brief the Security Council in New York while others will take samples they collected to labs in Europe.

Haq says the team has a "large number of facts" at its disposal and could "construct a narrative of what happened."

Diplomats from the five permanent Security Council members ended a second day of closed-door meetings on Syria Thursday with no consensus on possible military action.

Their meeting lasted less than an hour, and the ambassadors brushed past reporters without any comments.

President Barack Obama's top national security advisers are briefing members of Congress Thursday about intelligence on last week's alleged poison gas attacks that killed hundreds of civilians in the Damascus suburbs.

White House spokesman John Earnest says along with the circumstantial evidence that the Syrian military used chemical weapons on civilians, there is classified intelligence that undoubtedly points to an attack by the Syrian government.

Syrian officials deny using chemicals. They accuse the rebels of using such weapons on Syrian soldiers.

In London Thursday, British Prime Minister David Cameron told opponents of military action against Syria that taking no response sends President Bashar al-Assad a message that he can use chemical weapons with no fear of reprisal.