The inspectors from The Hague-based Organisation for the Prohibition of Chemical Weapons travelled by road from Lebanon a day after UN experts departed after probing a series of alleged chemical attacks.
Syria’s information minister meanwhile insisted that President Bashar al-Assad would stay in office and that he had the option to run for another term in elections next year.
Assad’s departure is a key demand of the opposition, who insist it must be a pillar of a mooted peace conference in Geneva.
And the Syrian Observatory for Human Rights NGO released a new toll in the conflict, saying more than 115,000 people had been killed since March 2011.
A first group of 20 OPCW inspectors are in Syria to implement a UN resolution ordering the elimination of Syria’s arsenal by mid-2014.
The arsenal is believed to include more than 1,000 tonnes of sarin, mustard gas and other banned chemicals stored at an estimated 45 sites across the war-torn country.
The OPCW said the inspectors — all volunteers — will meet Syrian government officials late Tuesday before setting off to work.
The mission is the first in OPCW history to take place in a country embroiled by civil war, and the inspectors are to check a list of sites provided by the Damascus regime and conduct on the spot testing.
The UN team that left Damascus on Monday probed 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 landmark UN Security Council resolution 2118.
Syria has already submitted detailed accounting of its chemical arsenal and Assad told Italian television his government “will comply” with the terms of the resolution.
The OPCW inspectors who arrived Tuesday at a five-star Damascus hotel from Lebanon in a 20-vehicle UN convoy, will give priority to chemical weapons production sites which are to be disabled by late October or early November.
“Expedient methods” will be used to render these production facilities unusable, said an OPCW official.
Peace conference bid
UN resolution 2118 calls for the convening of a much-delayed peace conference in Geneva as soon as possible, with UN Secretary General Ban Ki-moon setting a target date of mid-November.
“Syria is staying put: the state, the nation, the people and the president. This is the Syrians’ choice,” Information Minister Omran al-Zohbi told journalists on Tuesday.
“All the people call for President Bashar al-Assad to be president of this state, whatever the opposition, the Americans and the traitors say.”
Zohbi added that Assad has the “right to take a decision” on whether he will run for a new term in mid-2014, when his current mandate expires.
Foreign Minister Walid Muallem, speaking at the UN on Monday, also insisted no pre-conditions be set for the planned peace conference.
“It is now for those who claim to support a political solution in Syria to stop all hostile practices and policies against Syria, and to head to Geneva without preconditions,” he said.
On Tuesday, the Observatory said the toll since the beginning of the conflict had now reached 115,000 people, most of them fighters from both sides.
More than four million people have been displaced inside Syria, and more than 2.1 million have fled across its borders, becoming refugees.
On the ground, violence raged on Tuesday in flashpoints around the country, including north and east Damascus, and Aleppo province in the north, the Observatory said.
In the north, at least 20 rebel fighters, including from Al-Qaeda affiliate the Al-Nusra Front, were killed in army bombing intended to open a new supply route between central Syria and Aleppo city, the Observatory said.