Opposition activists in Syria say they have documented the deaths of more than 200 men, women and children in what they say is one of the worst massacres of the war.
Earlier this month the government said it had killed "terrorist fighters" in an operation in three neighbouring districts in al-Bayda and Baniyas in the west of the country, the BBC reports.
But graphic video footage and fresh eyewitness testimony appear to support claims that the area was witness to one of the worst atrocities of the conflict.
On 2 May, government troops and militias marched into al-Bayda, in Tartous province on Syria's Mediterranean coast, the BBC says. The following day they attacked neighbouring Baniyas.
Together government forces have described these operations as a "strike against armed terrorists".
State media reported 40 opposition fighters were killed but Syrian human rights activists and eyewitnesses say more than 200 civilians died and hundreds are missing in what they allege was a brutal sectarian attack against innocent civilians.