A new video released by the Daesh (IS) group on Sunday shows its fighters cutting off the heads of eight men said to be Shiites.
The video posted on social media said the men were beheaded in the central Syrian province of Hama.
The video could not be immediately independently verified, but it appeared genuine and corresponded to other AP reporting of the events.
The Britain-based Syrian Observatory for Human Rights also said that the video was authentic.
IS has beheaded scores of people since capturing large parts of Iraq and Syria last year in a self-declared caliphate.
In the video, the men, wearing orange uniforms with their hands tied behind their backs, were led forward in a field by teenage boys.
They were then handed over to a group of Daesh fighters. A boy wearing a black uniform hands out knives to the fighters, who then behead the hostages.
A fighter speaks in the video, using a derogatory term. The fighter said in the video that the current military campaign against Daesh will only make the militant group stronger.
"Our swords will soon, God willing, reach the Nuseiries and their allies like Bashar and his party," the man said referring to Syrian President Bashar Assad and Lebanon's militant Hezbollah group that is fighting on his side.
The word Nuseiry is a derogatory term to refer to Assad's Alawite sect.
In Lebanon, the state-run National News Agency quoted the family of Younes Hujairi, who was kidnapped from his hometown of Arsal near the Syrian border in January, as saying he had been beheaded.
NNA quoted members of Hujairi's family as saying they have seen pictures of a fighter carrying his severed head on social media.
It was not clear if Hujairi was one of one of the men beheaded in the video. Hujairi is a Sunni.
The border town of Arsal, where Hujairi was kidnapped, was also the site of a bold joint raid by the Daesh group and Syria's Al Qaeda-linked Nusra Front last August that captured two dozen Lebanese soldiers and policemen.
Four of those hostages have been killed so far, two of them beheaded. The remaining 20 soldiers and policemen remain hostages.