Bloodshed has disrupted civilian life across Syria since a violent government crackdown in early 2011 on peaceful demonstrations for democratic reform turned the unrest into an armed insurgency bent on overthrowing President Bashar al-Assad.

More than 50 countries asked the United Nations Security Council on Tuesday to refer the crisis to the International Criminal Court, which prosecutes people for genocide and war crimes. But Russia - Assad's long-standing ally and arms supplier - blocked the initiative, calling it "ill-timed and counterproductive.