By Chris Liakos, Claudia Colliva and Dalal Mawad, CNN

Paris (CNN) — France has issued an arrest warrant for Syrian President Bashar al-Assad over the alleged use of banned chemical weapons against civilians in Syria, a judicial source told CNN on Wednesday.

According to the source, two investigative judges on Tuesday issued four warrants against Assad, his brother Maher al-Assad, and two other senior officials, for complicity in crimes against humanity and complicity in war crimes.

Anwar al-Bunni, a Syrian human rights lawyer and a founder of the Syrian Center for Legal Studies and Research, told CNN the decision was “unprecedented.”

It is believed to be the first time a nation has issued an arrest warrant for crimes against humanity for a sitting head of state in another country.

An Interpol ‘Red Notice’ is expected to follow, according to Michael Chammas, one of the plaintiff’s lawyers, who spoke to CNN from Germany.

A Red Notice is a request to law enforcement worldwide to locate and provisionally arrest someone pending extradition, surrender, or similar legal action, according to Interpol.

“All Interpol member states should then comply with the arrest warrant,” Chammas told CNN.

The legal case was brought forward by the Syrian Centre for Media and Freedom of Expression (SCM), the Open Society Justice Initiative (OSJI) and the Syrian Archive in March 2021 “over the use of banned chemical weapons against civilians in the town of Douma and the district of Eastern Ghouta in August 2013, in attacks which killed more than 1,000 people,” the plaintiffs said in a statement Wednesday.

The Syrian government was accused of using poison gas in Ghouta, a suburb of Damascus, then a rebel stronghold that the regime had been desperately trying to take back for more than a year. It in turn accused opposition forces of carrying out the attacks themselves.

An investigation was opened “in response to a criminal complaint based on the testimony of survivors of the August 2013 attacks,” the plaintiffs’ statement read.

Lawyer Mazen Darwish, founder and director-general of the Syrian Center for Media and Freedom of Expression (SCM), said in a statement Wednesday that the decision “constitutes a historic judicial precedent.”

“It is a new victory for the victims, their families, and the survivors and a step on the path to justice and sustainable peace in Syria,” Darwish said.

Hadi al-Khatib, founder of the Syrian Archive, said: “With these arrest warrants, France is taking a firm stand that the horrific crimes that happened ten years ago cannot and will not be left unaccounted for. We see France, and hopefully, other countries soon, taking the strong evidence that we have gathered over years and finally demanding criminal responsibility from the highest-level officials.”

CNN is trying to reach the Syrian government for comment.

The Syrian government has long been accused of war crimes, but it has repeatedly insisted its strikes target “terrorists.” It has denied using chemical weapons.

“We have never used our chemical arsenal in our history,” Assad said in 2017. He added that “morally” the Syrian government would never do this “because it’s not acceptable.”