KYIV, Aug 4 (Reuters) - Kyiv police detained a man who forced his way into Ukraine"s main government building on Wednesday morning and threatened to detonate a grenade, head of the National Police Ihor Klymenko said. "We were able to get out of this situation, neutralize this criminal," Klymenko told a briefing. He said the man, whose demands were unclear, was identified as a veteran of the war with Russia-backed separatist in eastern Ukraine. Klymenko said the man had a real grenade and he had given himself up after talking to a friend and fellow veteran. Video on the incident online, which could not immediately be verified by Reuters, showed a man in jeans and a striped T-shirt in one of the lobbies of the building where government ministers meet. He is holding something in his right hand and is shouting that he has a grenade. The prime minister"s office is in the building, but it was not immediately clear if he or any other ministers were present at the time. The prime minister"s spokeswoman declined to comment.