Syria's Islamist-led government on Monday said it had completed a military operation against a nascent insurgency by Bashar al-Assad loyalists, as it faced Western demands for accountability over the reported killing of hundreds of civilians.

The commander of a Kurdish-led force in Syria said on Sunday the country's interim president must hold the perpetrators of communal violence in Syria's coastal areas to account, accusing Turkey-backed factions of being primarily behind the killings.

Syria's new leader has vowed accountability and an investigation after reports of mass killings of Alawite civilians triggered an international backlash against the worst violence since Bashar al-Assad's overthrow.

Alawites, a Shia sect, ruled Syria for decades under the Assads. Now, after Bashar al-Assad's fall, they face violence as sectarian tensions escalate in the war-torn country

A monitoring group says 973 civilians have been killed in revenge attacks against the Alawite sect since Thursday.

The death toll from two days of clashes between security forces and loyalists of ousted Syrian President Bashar al-Assad and revenge killings that followed has risen to more than 600, a war monitoring group said Saturday.