Britain and France called Tuesday for United Nations sanctions to be imposed on Syria after a UN-led investigation found the regime had carried out chemical attacks.
The UN ambassadors from London and Paris described the use of chemical weapons against civilians as a war crime ahead of a closed-door council meeting to discuss the investigation's findings.
French Ambassador Francois Delattre called for a "quick and strong Security Council response" that would include "imposing sanctions on those who are responsible for these acts."
US Ambassador Samantha Power did not specify what measures should be taken, but called on the Security Council to act swiftly to ensure those responsible for using chemical weapons "pay a price."
An investigative panel set up by the Security Council said in a report last week that President Bashar al-Assad's forces had carried out at least two chemical attacks, one in 2014 and one in 2015.
Previous reports from the Organization for the Prohibition of Chemical Weapons (OPCW) had concluded that toxic gases have been used as weapons in Syria's five-year war, but stopped short of identifying the perpetrators.
The panel of inquiry, known as the Joint Investigative Mechanism (JIM), for the first time pointed the finger of blame at the Assad regime for chemical weapons use after years of denial from Damascus.
British Ambassador Matthew Rycroft said the council will be "looking at the imposition of sanctions and some form of accountability within international legal mechanisms."
It is "essential that we have a robust international response" to impose "measures under chapter 7" of the UN charter, which provides for sanctions, he added.
- Will Russia back sanctions ? -
The push for sanctions against the Damascus regime is expected to face resistance from Russia, Syria's ally.
Russian Ambassador Vitaly Churkin praised the JIM for its professionalism, but declined to say what measures -- if any -- might be taken to follow up on the panel's findings.
The panel found that the Syrian regime had dropped chemical weapons on two villages in northwestern Idlib province: Talmenes on April 21, 2014 and Sarmin on March 16, 2015.
In both instances, Syrian air force helicopters dropped "a device" on houses that was followed by the "release of a toxic substance," which in the case of Sarmin matched "the characteristics of chlorine."
Chlorine use as a weapon is banned under the Chemical Weapons Convention, which Syria joined in 2013, under pressure from Russia.
Human Rights Watch called on the council to refer Syria to the International Criminal Court for war crimes and to urgently impose sanctions.
Britain, France and the United States said such a step remained an option, even though Russia and China blocked ICC referral in 2014.
"Russia and China don't have a leg to stand on by continuing to obstruct the Security Council on Syria sanctions and ICC referral," said Louis Charbonneau, UN director at Human Rights Watch.
"The Security Council diminishes its importance if it doesn't take strong action against demonstrated use of chemical weapons by the Syrian government," he said.