France says it is certain that the nerve agent sarin has been used in Syria on several occasions following tests it has carried out on samples recovered from the country.
"These tests show the presence of sarin in various samples in our possession," Foreign Minister Laurent Fabius said in a statement on Tuesday, adding that the test results had been handed to the United Nations.
"We have no doubt that the gas is being used ... the laboratory tests are clear," he told France 2 television about the blood and hair samples later on Tuesday. "There is no doubt that the regime and its accomplices" are using them, he added.
France has been testing samples of suspected chemical weapon elements for several weeks, including some smuggled out by reporters from the French daily Le Monde.
"It would be unacceptable that those guilty of these crimes remain unpunished," Fabius said.
Use of chemical weapons is illegal under international law.
An exiled chemist who worked on developing Syria's chemical weapons told Al Jazeera last month that the country's stockpile comprises 700 tons of sarin agent.
The UN Commission of Inquiry on Syria said that military and government leaders must be held accountable for implementing a "concerted policy" of human rights violations.
"War crimes and crimes against humanity have become a daily reality in Syria where the harrowing accounts of victims have seared themselves on our conscience," its report said.
Investigators said they had "reasonable grounds" to believe that limited amounts of chemical weapons had been used in Syria.
The inquiry said conclusive findings could be reached only after testing samples taken directly from victims or the site of the alleged attacks. It called on Damascus to allow a team of experts into the country.
PHOTO CAPTION
A citizen journalism image provided by Edlib News Network, ENN, which has been authenticated based on its contents and other AP reporting, show an anti-Syrian regime protester holding up an Arabic placard reading, "If America does not know who used the chemical weapons, so it could be flying saucers from another planet," during a demonstration, in Sarmada town, in Idlib province, northern Syria.
Al-Jazeera