Syrian security forces are alleged to have executed 52 people belonging to the Alawite minority in the coastal province of Latakia, according to one war monitoring group.
Footage seen by the British-based Syrian Observatory for Human Rights shows dozens of bodies in civilian clothing piled up in the garden of a house in Latakia.
An interior ministry source told the country’s official news agency Sana said that “individual violations” had occurred on the coast and pledged to put a stop to them.
BBC News has not been able to verify claims that the killings were committed by the forces of Syria’s new rulers.
This followed clashes between government forces and fighters loyal to the deposed President Bashar al-Assad, which left more than 70 dead.
A curfew has been imposed in the cities of Homs, Latakia and Tartous, where the fighting has broken out.
Earlier, BBC Verify confirmed two videos that showed a body being dragged behind a car in Latakia.
The United Nation’s special envoy for Syria, Geir Pedersen, said in a statement he was “deeply concerned” by reports of the clashes and killings.
He called on all parties to “refrain from actions that could further inflame tensions, escalate conflict, exacerbate the suffering of affected communities, destabilize Syria, and jeopardize a credible and inclusive political transition.”
The region is the heartland of the Alawite minority, and a stronghold of the Assad family, which belong to the sect.
Estimations of the number of people killed in the violence vary, and the BBC has been unable to independently verify them.
Residents say they have been the targets of sectarian violence, with one Alawite woman telling BBC Arabic that many Syrians are “scared” regardless of if they were on the coast or in the capital.
She added that “everyone is terrified from the current incitement”, and fears they will become “scapegoats”.
Turkey and Russia have warned that the bloodshed, the worse since the toppling of Assad in December, threatens the stability of the entire region.
Alawites, whose sect is an offshoot of Shia Islam, make up around 10% of Syria’s population, which is majority Sunni.
