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.