IS released a video showing the beheading of what it described as a Russian intelligence officer captured in Syria, the US-based SITE monitoring website reported on Tuesday.
The video, which is in Russian and 12 minutes long, was released on the day Moscow celebrates its 1945 victory anniversary over Nazi Germany.
The video includes military parades and shows a man dressed in a black jump suit kneeling in a desert scene as he urges other Russian agents to surrender.
“This idiot believed the promises of his state not to abandon him if he was captured,” a narrator says in the recording.
Shortly afterwards the man is beheaded by a bearded man dressed in combat fatigues.
The authenticity of the video has not been verified and nor is it clear when the beheading took place. The video, however, claimed that the beheading happened in the aftermath of Russian bombing raids over Syria.
However, the Russians pointed out that none of their servicemen had been captured nor killed by IS in Syria.
Russian news agencies reported that the Defense Ministry in Moscow stated said all Russian forces in Syria were accounted for and that the struggle against terrorism would continue.
Nevertheless, Russian senator Vikor Ozerov told Interfax news agency “there would be hell to pay” if the recording proved authentic.
Syrian President Bashar Assad is being backed militarily by the Russians in his war against rebels seeking to oust him.
According to the Russian Defence Ministry, about 30 Russian servicemen have been killed since the start of the Kremlin’s operation there in September 2015.