Two United Nations inspectors arrived Wednesday in Damascus to investigate claims that chemical weapons have been used in Syria's 28-month-old civil war, UN sources in Beirut told dpa.
Ake Sellstrom and Angela Kanen were to meet with Syrian officials to discuss securing access to areas where past use of the toxin sarin was suspected, added the sources on condition of anonymity.
There was no immediate comment from Damascus.
The visit comes after the UN accepted in June an invitation from the government of Syrian President Bashar al-Assad to carry out investigations in the area of Khan al-Assal, in the northern province of Aleppo, where chemical weapons were reportedly used.
Khan al-Assal was the scene of deadly fighting in March between government troops and opposition rebels. Both sides accused the other of launching a deadly chemical attack in the town.
The opposition retook Khan al-Assal from the Syrian army earlier this week.
Britain, France and the United States have presented evidence in recent months of other suspected chemical attacks in Syria, which they blamed on al-Assad's troops.
In Paris, the head of Syria's main opposition alliance, Ahmed al-Jarba, was to hold talks later Wednesday with President Francois Hollande on the sensitive question of arming the rebellion.
France was the first country last year to recognize the opposition Syrian National Coalition and, more recently, to confirm the use of chemical weapons by al-Assad's regime. However, it has balked at arming the rebels.
Al-Jarba arrived in Paris Tuesday at the start of a tour that will take him to New York later in the week for talks with UN Security Council members, including Russia.
He was accompanied to Paris by General Selim Idriss, head of the rebel Free Syrian Army.
In a hearing with the foreign affairs committee of the French National Assembly Tuesday evening, the two men repeated their appeals for military aid.
France says it has not received sufficient guarantees that weapons would not end up in hands of radicals fighting to topple al-Assad.
Al-Jarba told French media the protracted nature of the conflict had contributed to the rise of fundamentalist groups. "The longer it lasts, the more it favours them," he was quoted as saying.