Three NGOs have filed a criminal complaint in France against the government of Syrian President Bashar al-Assad over chemical weapons attacks in 2013, they said on Tuesday.
Accusing the Assad regime of "crimes against humanity" and "war crimes", the three organisations appealed to a Paris court to use its extra-territorial powers which allow it to judge cases outside France.
The Syrian Center for Media and Freedom of Expression (SCM), the Open Society Justice Initiative (OSJI) and the Syrian Archive filed the case on Monday.
They are hoping that the court will investigate chemical attacks with sarin gas -- which is outlawed under the international Chemicals Weapons Convention -- in August 2013 in the city of Douma, and in eastern Ghouta near the capital Damascus.
According to the US government, close to 1,400 people died in the attacks. The Syrian government denies responsibility.
The case, which is based on witness statements, photos and an analysis of the Syrian military's chain of command, should "ascertain the responsibility of those who ordered and implemented these attacks", the NGOs said.
"We believe there is strong evidence of what happened that day," Mazen Darwish, president of Paris-based SCM, told AFP.
"It's very important to send a message to the perpetrators that survivors will keep fighting for truth and accountability," he said.
With the evidence gathered, the NGOs were giving France and other western governments "the key, the legal possibility to act in a political and legal way".
Failure to act on the evidence would mean "that we give the green light for all dictatorships to use chemical weapons".
Syrian Archive director Hadi al Khatib said in the statement that the Syrian government "has to be held responsible" for the attacks.
He alleged that it had failed to be transparent about its production, use and stockpiling of chemical weapons.
The NGOs said they hoped that France would cooperate with prosecutors in Germany, where they had already lodged a case in October last year concerning the alleged use of chemical weapons in April 2017 in a region between Damascus and Aleppo.
After the 2013 attacks the Syrian government promised to dismantle its stock of chemical weapons.
But according to a report released last October by OSJI and Syrian Archive, the Syrian government is still running a "robust" chemical weapons programme.
burs/jh/cb/mjs