Average monthly losses of the Ukrainian armed forces amount to about 50,000 people in the past six months, according to the Russian ministry.
"About 100,000 Ukrainian servicemen, according to official data, have arbitrarily left their military units and gone on the run," the ministry said in a statement.
The pace of mobilisation in Ukraine does not help Kiev in replenishing losses, and this leads to reduction in the number of Ukrainian servicepeople, the ministry added.
"Legislative changes prepared under pressure from Western countries by the Kiev regime to lower the mobilisation age from 25 to 18 are the only way for [Volodymyr] Zelensky to delay the cascading collapse of the front in Donbass for a few more months," the ministry said.