More than 700 civilians of the Alawite religious minority have been killed, the British-based Syrian Observatory for Human Rights says.

Syria's government on Sunday announced a probe after the killing of Alawite civilians triggered an international backlash against the worst violence since Bashar al-Assad's overthrow.

Security forces from the new Syrian regime are said to have killed 700 in former President Assad's coastal heartland. The President has called for calm.

International alarm is growing over fighting in western Syria, where hundreds of civilians have been reportedly killed amid intense clashes.

More than 1,000 people have been killed in fighting between forces of the new government and remnants of the ousted regime, according to a war monitor, which said about 700 were civilians.

More than 1,000 people, most of them civilians, have been killed in Syria over the last several days according to the Syrian Observatory for Human Rights. The conflict is between remaining loyalists to ousted President Bashar al-Assad and forces belonging to the country’s new government which took over after Assad fled the country in December.