Beirut: Human Rights Watch and the Syrian opposition National Coalition have condemned a gruesome video apparently showing a Syrian rebel fighter cutting out the heart of a regime soldier and eating it.

“International news agencies and social media websites have been circulating a video clip in which a person claiming to be a member of the rebels in Homs performs a horrific and inhumane act,” the National Coalition said.

“The Syrian Coalition strongly condemns this act - if it is revealed to be true. The Coalition stresses that such an act contradicts the morals of the Syrian people, as well as the values and principles of the Free Syrian Army.”

Human Rights Watch said the man depicted in the video appeared to be from a rebel brigade in central Homs province that fired indiscriminately at Lebanese villages earlier this year.

“It is not enough for Syria’s opposition to condemn such behaviour or blame it on violence by the government,” said Nadim Houry, Middle East deputy director at Human Rights Watch.

“The opposition forces need to act firmly to stop such abuses.”

In the video, a man identified as Abu Sakkar, an alleged commander of the Omar Farouq brigade, is shown standing over the body of a uniformed soldier.

“We swear to God we will eat your hearts and livers, you soldiers of Bashar the dog,” he says as he cuts out the heart in the amateur footage uploaded to YouTube.

“We are the heroes of Baba Amr,” he says, referring to a rebel stronghold of the central city of Homs that has been flattened by President Bashar Al Assad’s forces.

The man then stands up, raises his dagger in one hand and the heart in the other and raises it to his mouth before the video abruptly ends.

“The Syrian Coalition reiterates its condemnation of such an act and stresses that it is a crime, regardless of the perpetrator,” the group said.

“The culprit will eventually be tried in court in front of an honest and fair judiciary.”

The Syrian conflict started with peaceful protests in March 2011, but when these were suppressed it gradually turned into an increasingly sectarian civil war which, according to one opposition monitoring group, has cost more than 80,000 lives.

Majority Sunnis lead the revolt, while Al Assad - whose family have ruled for over four decades - gets his core support from his own Alawite sect, an offshoot of Shiite sect.

Peter Bouckaert of Human Rights Watch said that he had seen an original, unedited copy of the video and that Abu Sakkar’s identity had been confirmed by rebel sources in Homs and by images of him in other videos wearing the same black jacket as in the latest clip and with the same rings on his fingers.

“The mutilation of the bodies of enemies is a war crime. But the even more serious issue is the very rapid descent into sectarian rhetoric and violence,” said Bouckaert.

He said that in the unedited version of the film, Abu Sakkar instructs his men to “slaughter the Alawites and take their hearts out to eat them”, before biting into the heart.

Abu Sakkar has been seen in previous videos firing rockets at Lebanese Shiite villages on the border and posing with the body of a soldier purportedly from the Lebanese Shiite militant Hezbollah group, which is helping Al Assad’s forces.

Reuters cannot independently verify videos from Syria, where access is restricted by the government and security constraints.