The New York Times on Thursday, shows the militants, believed to be members of the Jund al-Sham group, standing over seven shirtless men kneeling face-down before them. Five were trussed, their backs showing signs of torture.
In the video, the rebels’ commander -- known as “the Uncle” -- is seen reading a bitter revolutionary verse and then fires a bullet into the back of the first prisoner’s head. His gunmen followed suit, promptly shooting all the men at their feet.
The footage ends abruptly after the militants dump the soldiers’ bodies into a well.
The video was filmed in April near Idlib, a city in northwestern Syria, and was smuggled out of Syria by a former rebel who decided to make a break with the militants and flee the country because of such cold-blooded murders.
It is the latest in a growing series of accounts of rebel savagery in the country.
Last month, another video emerged on the Internet, which showed the al-Qaeda-affiliated group al-Nusra Front militants pouring a flammable liquid on three hand-cuffed, blind-folded men, who appeared to be Syrian Kurd soldiers.
The militants then pushed the three into a fire they had made.
The latest video has been aired at a time when US President Barack Obama is trying to convince Congress to approve a military strike against Syria over the alleged use of chemical weapons by the Syrian government.
Washington says it has obtained evidence proving the Syrian army was behind the chemical attack near Damascus on August 21, which killed hundreds of Syrians.
The Syrian government has repeatedly said that the deadly attack was carried out by militants operating inside the country in a bid to draw in a foreign military intervention.
On Tuesday, US Secretary of State John Kerry testified before the US Senate Foreign Relations Committee on the issue of radicalized rebels in Syria.
Kerry said that the assumption that the Syrian opposition had become more infiltrated by al Qaeda was "basically incorrect" and that the opposition has "increasingly become more defined by its moderation."
On Wednesday, Russian President Vladimir Putin called Kerry a liar, saying the US secretary of state denied that al-Qaeda was operating in Syria.
“This was very unpleasant and surprising for me. We talk to them (the Americans) and we assume they are decent people, but he is lying and he knows that he is lying. This is sad," Putin said to his human rights council.
Syria has been gripped by deadly unrest since 2011. According to reports, the Western powers and their regional allies -- especially Qatar, Saudi Arabia, and Turkey -- are supporting the militants operating inside Syria.
In a statement issued on Tuesday, the United Nations High Commissioner for Refugees (UNHCR) said the number of Syrian refugees, who have fled the country’s 29-month-long conflict, reached two million.
“Syria is hemorrhaging women, children and men who cross borders often with little more than the clothes on their backs,” the UNHCR said.
The UN refugee agency also said some 4.2 million people have also been displaced inside Syria since the beginning of the conflict in the Arab country.
A gruesome video has emerged which shows foreign-backed militants in Syria killing seven captured government soldiers execution style.
The video, which was released by