DUBAI -- ISIS has issued 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 Russian Defence Ministry and the FSB security service were not immediately available for comment.

The 12-minute Russian-language video, released on the day Russia celebrates the anniversary of the 1945 victory over Nazi Germany with military parades, showed the man dressed in a black jump suit kneeling in a desert scene and urging other Russian agents to surrender.

"This idiot believed the promises of his state not to abandon him if he was captured," he said before a bearded man beheaded him with a knife.

The authenticity of the recording and the identity of the man could not immediately be verified, nor was it clear when the killing occurred.