Russian Foreign Minister Sergei Lavrov said that U.S. plans to send weapons to Ukraine, fighting pro-Russian rebels in its east, would be a direct hit against a Minsk peace agreement struck last month, RIA news agency reported.

Ukraine has requested lethal aid from the United States, where Congress wants a tougher response from President Barack Obama after claims by U.S. intelligence agencies of Russian tanks and artillery crossing into Ukraine.

Moscow denies the claims.