Moscow, August 29 (RHC)-- The Russian Defense Ministry has rejected claims of its troops' involvement in the escalating fighting between Ukrainian forces and pro-Moscow forces in the east.

Russia's Defense Ministry spokesman Igor Konashenkov told Russian news agencies on Thursday that this "information has no relation to reality" and that army units believed by the U.S. to have crossed into Ukraine were conducting "tactical training exercises on their own and outlying ranges."

These comments have been the first reaction by a senior Russian official since the U.S. ambassador to Kiev accused Moscow of providing air defense systems to pro-Russia forces in Ukraine and becoming "directly involved in the fighting."

Ukraine's mainly Russian-speaking regions in the east have been the scene of deadly clashes between pro-Moscow forces and the Ukrainian army since Kiev launched military operations to stifle the pro-Russian protests in mid-April.

Kiev has accused Moscow of meddling with the deadly conflict in eastern Ukraine. However, Moscow has repeatedly rejected the allegations.