In the nearly six-minute video, Ukrainian soldiers are heard saying they have captured a Russian reconnaissance team operating from Olkhovka, a settlement in Kharkov, about 20 miles from the Russian border. Asked about the video, a senior presidential adviser, Oleksiy Arestovych, said in an interview posted on YouTube on Sunday: “The government is taking this very seriously and there will be an immediate investigation. We are a European army and we are not kidding. “It is completely unacceptable behavior.” In a separate statement, Arestovic said: “We treat detainees in accordance with the Geneva Convention, regardless of your personal emotional motives.” CNN contacted the Ukrainian Ministry of Defense for comments. In response, the ministry sent a statement to CNN statement from Chief of Staff Valerii Zaluzhnyi. The statement did not directly address the incident, but said: “In order to discredit the Ukrainian defense forces, the enemy is filming and distributing videos showing the inhuman treatment of ‘Russian prisoners’ by alleged ‘Ukrainian soldiers.’ “I emphasize that the military of the Ukrainian Armed Forces and other legitimate military formations strictly adhere to the rules of international humanitarian law,” Zaluzny said. “I urge you to take into account the reality of the information and psychological warfare and to trust only official sources.” It is not clear which Ukrainian unit may be involved. The soldiers speak in a mixture of Ukrainian and Russian with a Ukrainian accent. The video comes as Ukrainian forces make gains east and south of Kharkov. CNN spotted and verified a large video uploaded to a telegram on Saturday showing a successful attack by Ukrainian troops of the Azov Battalion, in which a number of Russian prisoners were captured in a rapid attack on Olkhovka, also known as Vilkhivka. Some of the detainees were undressed and their eyes were blindfolded. This video was posted by Konstantin Nemichev, a Kharkiv regional official involved in the Olkhovka attack. He told CNN that it had nothing to do with the video that showed Ukrainian troops kneeling before Russian prisoners. “This is not our site. I have not seen such a site,” he told CNN on Sunday. He suggested that the video was shot “maybe somewhere in the [Kharkiv] region.” In the first response from the Russian authorities, the chairman of the commission of inquiry of the Russian Federation, AI Bastrykin, said that an investigation would be launched “to determine all the conditions of ill-treatment of captured soldiers by Ukrainian nationalists.” In a statement, Bastrykin said: “Scenes have surfaced on the Internet in which Ukrainian nationalists have been treated with extreme severity. A video circulating on the Internet shows captured soldiers being shot in both legs and receiving no medical treatment. “It is illegal. The actions took place in one of the bases of Ukrainian nationalists in the Kharkiv region.” CNN does not show the video.