The UN team investigating allegations of chemical weapons attacks on rebels leaves Syria as the US says it is considering military action.
UN personnel were seen entering Lebanon from Syria and driving in a convoy to Beirut’s airport.
The weapons inspectors spent four days gathering evidence at the site of alleged Syrian government nerve gas attacks on rebel-held suburbs of the Syrian capital earlier this month.
They have taken blood and urine samples from victims and soil samples for laboratory examination.
The team’s departure came just hours after US President Barack Obama said he was considering a military strike against the Syrian government.
Mr Obama said: “We cannot accept a world where women and children and innocent civilians are gassed on a terrible scale.
“This kind of attack threatens our national security interests by violating well established international norms against the use of chemical weapons by further threatening friends and allies of ours in the region, like Israel and Turkey, and Jordan and it increases the risk that chemical weapons will be used in the future and fall into the hands of terrorists who might use them against us.”
He added: “We’re not considering any open-ended commitment. We’re not considering any boots-on-the-ground approach. What we will do is consider options that meet the narrow concern around chemical weapons.
The US has accused the Assad regime of killing at least 1,429 people including more than 400 children – far more than previous estimates in the alleged chemical attack.
Read more: Syria chemical attack - the video evidence
The Syrian government said the accusations were “flagrant lies” and compared them to the false claims that Saddam Hussein had weapons of mass destruction before the Iraq War.
The US has warships armed with cruise missiles in place in the eastern Mediterranean near Syria’s coastal waters.
But France is the only major international ally supporting military action after British MPs voted against a government motion sanctioning military action to protect Syrian civilians.
There was tension in Damascus on Saturday, with residents stocking up on food and other necessities in anticipation of strikes, but no sign of panic.