More than 40 people have been killed by government forces in a village in north-western Syria, activists say.
The Syrian Observatory for Human Rights and Violations Documentation Centre both listed the names of people they said were executed in al-Bayda, near the port of Baniyas, on Thursday.
An online video appears to show seven bodies in pools of blood. State media blamed the incident on “terrorists”.
The main opposition group accused the government of a “large-scale massacre”.
“It is time for the world to intervene and put an end to the grievous crimes of the Assad regime,” the National Coalition said in a statement.
On Friday, the Syrian Observatory, a UK-based activist group that monitors human rights violations on both sides of the conflict via a network of contacts, said the army was bombarding Sunni areas in Baniyas.
‘House-to-house searches’
In al-Bayda, at least 50 people had been “summarily executed, shot to death, stabbed or set on fire” on Thursday, it said.
The killings were carried out by government troops, supported by pro-government militiamen known as “shabiha”, it added.
“Dozens of civilians from al-Bayda have gone missing, and we don’t know whether they have been arrested, killed or fled,” said the group’s director, Rami Abdul Rahman.
“Many villagers have fled to Sunni districts in southern Baniyas, as there is no refuge for them in Alawite areas.”
Mr Abdul Rahman said troops were still in al-Bayda on Friday, conducting house-to-house searches. Telephone and internet services to the village had been cut, he added, making it difficult to verify reports.
Syrian state media reported that “a number of terrorists” had been killed when government forces captured a cache of arms and ammunition in the area.
Al-Bayda is reportedly a predominantly Sunni Muslim village located in an area inhabited largely by members of President Bashar al-Assad’s Alawite sect, a heterodox offshoot of Shia Islam.
The BBC’s Jim Muir, who is neighbouring Lebanon, says the alleged incident highlights the sectarian nature of Syria’s conflict, as the Alawite-dominated government struggles for survival against an uprising rooted in the majority Sunni community.
Our correspondent says another incident likely to fuel sectarian tensions has been reported on Facebook – the desecration of a shrine near Damascus for a revered figure among Shia, Hajar ibn Adi.
Meanwhile, on the outskirts of Damascus on Friday, state media reported that rebels fired two rockets at the international airport.
The report said the rockets damaged a commercial aircraft and set a fuel depot on fire before the blaze was brought under control.
On Thursday, President Barack Obama said the US would look at all options to end the conflict in Syria. US Defence Secretary, Chuck Hagel, said Washington was rethinking its opposition to arming the rebels.
Mr Obama said he would not rush into a decision, and wanted to ensure action did not make the situation in Syria more deadly or complex.
More than 70,000 people have died over the last two years in Syria, according to the UN. More than a million have fled the country, with millions more displaced internally.
