President Vladimir Putin will on Friday meet the mothers of soldiers fighting in Ukraine, the Kremlin said, as the deadliest conflict in Europe since World War Two grinds into its 10th month.

The war in Ukraine has killed and wounded tens of thousands of soldiers on both sides, according to the United States, and the Russian invasion has triggered the biggest confrontation between Moscow and the West since the 1962 Cuban Missile crisis.

Hundreds of thousands of Russian soldiers have been sent to fight in Ukraine - including some of the more than 300,000 reservists who were called up as part of a mobilisation announced by Putin in September.

"On the eve of Mother's Day, which is celebrated in Russia on the last Sunday of November, Vladimir Putin will meet with the mothers of servicemen participating in the special military operation," the Kremlin said in a statement.

The Kremlin said Putin would meet with mothers of reservists called up to fight as well as professional soldiers of the armed forces.

Putin has said he has no regrets about launching what he calls Russia's "special military operation" against Ukraine and casts the war as a watershed moment when Russia finally stood up to an arrogant Western hegemony after decades of humiliation in the years since the 1991 fall of the Soviet Union.

Ukraine and the West say Putin has no justification for what they cast as an imperial-style war of occupation. Ukraine says it will fight until the last Russian soldier is ejected from its territory.

Ukraine does not disclose its losses. Russia last publicly disclosed its losses on September 21, when Defence Minister Sergei Shoigu said 5,937 Russian soldiers had been killed. But that number is far below most international estimates.

The United States' top general estimated on Nov. 9 that Russia and Ukraine had each seen more than 100,000 of their soldiers killed or wounded. (Reporting by Guy Faulconbridge)