Russian President Vladimir Putin stressed on Saturday "the unacceptable nature of the military-biological activities of the United States in Ukraine" in a phone conversation with Luxembourg`s Prime Minister Xavier Bettel, the Kremlin said in a statement.

Such activities pose a huge danger to both Russia and the whole Europe, Putin was quoted as saying by Xinhua news agency. The two leaders discussed Russia`s military operation in Ukraine, and Putin noted the missile attacks by the Ukrainian security forces on cities in Donbass, said the statement.