Opposition fighters from Islamist brigades have killed at least 21 civilians and 20 pro-regime fighters in an Alawite village in Syria's Hama province, an NGO said on Monday.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said fighters from Islamist brigades including Jund al-Aqsa were behind the deaths in Maan village, in central Syria, on Sunday.
Observatory director Rami Abdel Rahman said there were no immediate details on how the civilians had been killed, but added that at least 10 of them appeared to be from a single family.
The group said at least 20 members of the National Defence Forces, a pro-regime militia, had been killed in the attack.
A video posted on the YouTube website, purportedly produced by Jund al-Aqsa, showed its forces moving into the village and opening fire.
The video, titled "the liberation of Maan village," shows a fighter raising a black flag often associated with radical Islamist groups atop a communications tower.
A man wearing camouflage trousers and a shirt is shown lying on the ground, his upper chest soaked in blood, and fighters can be seen loading captured ammunition onto a truck.
There is no footage of the reported civilian deaths.
Syria's President Bashar al-Assad is a member of the Alawite minority, whose faith is an offshoot of Shiite Islam.
The uprising against him is dominated by Sunni Muslims and has attracted a number of extremist groups, who consider non-Sunni Muslims to be infidels.