Chemical weapons such as chlorine have been used in a "systematic manner" in Syria, according to an initial report by a team from the world's watchdog investigating alleged attacks there.
The report has not been publicly released, but the United States delegate to the Organisation for the Prohibition of Chemical Weapons (OPCW) quoted from it at an OPCW meeting.
Evidence uncovered by the fact-finding mission, which came under attack while probing the allegations, supports the conclusion that "toxic chemicals, most likely pulmonary irritating agents such as chlorine, have been used in a systematic manner in a number of attacks."
The allegations of chlorine use "cannot be dismissed as unconnected, random, or of a nature attributable to purely political motives," the report said.
The OPCW said in a statement that the investigation evidence "lends credence to the view that toxic chemicals - most likely pulmonary irritating agents, such as chlorine - have been used in Syria."
France's delegate said that the report "confirms that there was indeed (chlorine) use," according to a copy of his statement.
Syria has already shipped out 92% of its stockpile of chemical weapons under the terms of a UN-backed and US-Russia brokered deal agreed last year.
However, 8% of its stockpile remains at one site and cannot be taken to Latakia port because of the security situation.
The chlorine probe came after France and the United States alleged that President Bashar al-Assad's forces may have unleashed industrial chemicals rebel-held village in recent months.
Syria did not have to declare its stockpile of chlorine, a weak toxic agent that can be considered a chemical weapon if used offensively, as part of the disarmament deal as it is widely used for commercial and domestic purposes.
Danish and Norwegian ships are to take all of Syria's chemicals from Latakia port to a US ship for destruction at sea, along with sites in Finland, the US and Britain, by a now-impossible 30 June deadline.
The deal was reached after a sarin nerve gas attack in a rebel-held Damascus suburb killed around 1,400 people. Damascus agreed to hand over its chemical arsenal after the US threatened airstrikes against Mr Assad in response.