US Secretary of State John Kerry expresses concern to Moscow over reports of Russian military build-up in Syria, the state department says.

The UN's humanitarian chief Stephen O'Brien says he is "horrified" by the attacks on civilians taking place in Syria.

At least 80 people are killed Sunday in a string of Syrian government air strikes on a marketplace in Douma, a rebel-held town near Damascus

Islamic State (IS) militants kills more than 120 civilians since launching a fresh attack on the Syrian border town of Kobane, activists say.