An international chemical weapons watchdog expressed "grave concern" on Wednesday over the alleged use of such prohibited weapons in Syria.
In a statement, the Organization for the Prohibition of Chemical Weapons (OPCW) said the agency's fact-finding mission would continue investigating "all credible allegations and provide reports" over the alleged used of chemical weapons in Syria.
The mission's report will take into account corroboration between interviewee testimonies, open-source research, medical reports and other relevant documentation as well as the characteristics of any samples obtained by the mission, it said.
OPCW Director-General Ahmet Üzümcü said: "Any use of chemical weapons is a violation of the Chemical Weapons Convention and the hard-won international norm prohibiting these weapons.
"Those responsible for their use must be held accountable. These abhorrent weapons have no place in the world today," Üzümcü added.
On Monday, the U.S. State Department said it is "gravely alarmed" over reports of chemical attacks by the Syrian regime.
"The United States is gravely alarmed by continued allegations of the use of chlorine gas by the Syrian regime to terrorize innocent civilians, this time in Idlib province near Saraqib," it said in a statement.
Emphasizing that the attack is the sixth reported instance in the past 30 days in Syria, the State Department urged the international community to demand Syria cease using chemical weapons.
Located in northern Syria near the Turkish border, Idlib was declared a de-escalation zone, according to a cease-fire agreement last May reached in Kazakhstan's capital Astana.
The Syrian regime, however, has repeatedly violated the deal and has targeted residential areas in opposition-held, no-tension zones like Idlib.
Controlled by anti-regime armed groups, the province has been under intense airstrikes for the past two months. In January alone, 211 civilians were killed and 1,447 wounded.
Syria has been locked in a devastating civil war since March 2011, when the Assad regime cracked down on pro-democracy protests with unexpected ferocity.
While UN officials say hundreds of thousands of people have been killed in the conflict, regime officials say the death toll is closer to 10,000.
