A Syria pro-regime militia killed 13 members of the same family, including six children, in the Mediterranean coastal village of Bayda, a watchdog charged on Sunday.
"The number of people from one family who were killed by regime forces in the village of Bayda... has risen to 13," said the Syrian Observatory for Human Rights.
The killings came to light one day after they occurred, while fierce clashes pitting rebels against troops raged in Banias nearby.
"The three men, unarmed, were shot dead outside their home. The militiamen then broke in, and killed the women and the children," Observatory director Rami Abdel Rahman said.
He did not know how the women and children were killed by what he said were members of the pro-regime National Defence Force.
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"We have conflicting reports. Some say they were shot dead, others that they were burnt alive," he added.
Abdel Rahman attributed the violence to a revenge attack motivated by sectarian hatred.
"The Banias area is home to a mixture of Sunnis and Alawites. On Saturday, four Alawite members of the National Defence Force were killed in fighting there," he told AFP.
"The pro-regime militiamen took revenge for their deaths by killing this family," he added.
On May 2 and 3, some 300 people were massacred in Banias and Bayda, according to a toll compiled by the Observatory.
While Banias was one of the first towns to see demonstrations calling for the ouster of President Bashar al-Assad's regime, its location in Tartus province -- an Alawite bastion -- has prompted particularly fierce crackdowns there.