Swedish scientist Ake Sellstrom and Angela Kane, the UN high representative for disarmament, "have left Damascus after an official two-day visit, during which the experts met with Syrian officials" including Foreign Minister Walid Muallem, said UN media and communications analyst Khaled Al Masri.
The Damascus-based UN official gave no details on the discussions.
Meanwhile, UN Secretary General Ban Ki-moon told reporters in New York: "I will get the report, since they are coming out of Syria now; we will get the report soon."
President Bashar al-Assad's regime has insisted that the rebels were responsible for the alleged chemical attack there in March.
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Khan al-Assal fell from regime control and into rebel hands on Monday, complicating any effort to send in inspectors to visit the site.
The United Nations says Damascus has refused bids to investigate British and French claims that chemical attacks have also hit Homs in central Syria.
Syria's regime and rebels fighting to topple it have accused each other of using chemical weapons in the drawn-out conflict which has seen more than 100,000 people killed.