US 'Deeply Disturbed' by Reports of Chemical Weapons in Syria: John Kerry

The United States is deeply disturbed by reports that Syrian government forces attacked the town of Sarmin using chlorine as a weapon on March 16, Secretary of State John Kerry said in a statement on Thursday.

"We are looking very closely into this matter and considering next steps," he said. "While we cannot yet confirm details, if true, this would be only the latest tragic example of the Assad regime's atrocities against the Syrian people, which the entire international community must condemn."

A group monitoring the Syrian civil war said on Tuesday that government forces carried out a poison gas attack that killed six people in the northwest, and medics have posted videos of children suffering what they said was suffocation.

But a Syrian military source described the report of an attack on the town in Idlib province as propaganda.

Kerry has been getting tough on Syria in recent days after raising concerns among Middle East allies that the United States is open to negotiating with Assad, who has been fighting Islamist and other rebels since 2011.

The State Department has said the United States is seeking a negotiated political settlement but one that excludes Assad.