U.N. Secretary-General Ban Ki-moon is urging world powers to hold off on possible military action against Syria until a U.N. chemical weapons inspection team completes its work in the country.
Mr. Ban said Thursday that the team will leave the country by Saturday and report its findings to him.
He said "diplomacy should be given a chance" as the U.S. and other Western powers consider their response to the Syrian government's alleged use of chemical weapons against civilians last week.
The U.N. team left Damascus in a convoy on Thursday to begin its third day of inspections.
British Prime Minister David Cameron is facing stiff opposition from some members of parliament as he tries to make the case for his country's possible role in any military action in Syria.
During a Thursday session, some lawmakers questioned if British military action would draw the country further into Syria's civil war. Cameron argued that no response would send Syrian President Bashar al-Assad a message that he could use chemical weapons with no fear of reprisal.
In Washington, President Barack Obama's top national security advisers plan to brief members of Congress, on Thursday, about intelligence on the alleged poison gas attacks that killed hundreds of civilians in Damascus suburbs.
Mr. Obama says he has not decided on any action, but he has vowed that those who break international norms need to be held accountable.
The U.S. Navy deployed a fifth destroyer to the eastern Mediterranean region. Defense officials say the USS Stout will eventually replace another ship in the region but they did not say when the switch would take place.
The Syrian government denies having any role in the alleged gas attacks. And state media reports say Syrian President Bashar al-Assad said Thursday his country would defend itself against any aggression and emerge "victorious."