A chemical weapons disarmament team has arrived in Damascus to begin evaluating the country's arsenal of the banned weapons.
The inspectors from The Hague-based Organisation for the Prohibition of Chemical Weapons travelled by road from Lebanon on Tuesday, a day after UN experts departed after probing a series of alleged chemical attacks.
The team of 19 inspectors will begin a complex mission of locating and dismantling an estimated 1,000-tonne chemical arsenal as the civil war rages in Syria.
"In the coming days, their efforts are expected to focus on verifying information provided by the Syrian authorities and the initial planning phase of helping the country destroy its chemical weapons production facilities," a UN statement said.
They have about nine months to complete their task to have the Syrian regime destroy its chemical stockpile by mid-2014.
The team was unable to fly to Damascus, because the road between the airport and the city is the scene of frequent fighting.
The group replaces an outgoing UN team of chemical arms experts that has ended its second mission to Syria to probe seven alleged gas attacks and hopes to present a final report by late October.
Earlier this month it submitted an interim report that confirmed the use of the nerve agent sarin in August 21 attacks on the outskirts of Damascus.
The United States threatened military action in response, accusing forces loyal to Assad of deliberately killing hundreds of civilians with rocket-delivered nerve agents.
Syria denied the allegations, but agreed to relinquish its chemical arsenal, effectively heading off a strike, under a US-Russian deal which was enshrined in the landmark UN resolution.
"At this point, we have absolutely no reason to doubt the information provided by the Syrian regime," an OPCW official said on Sunday.
In his first comments since the UN resolution was passed on Friday, President Bashar al-Assad on Sunday told Italy's Rai News 24 his regime "will comply".
The Syrian conflict has killed more than 115,000 people since March 2011, according to figures released on Tuesday by the UK-based Syrian Observatory for Human Rights.