Shapovalov worked as a military aid liaison in Germany and previously commanded Ukraine's southern military district.

In his evening address, Zelensky said he hoped Shapovalov would bring "real combat experience" to the role and called for changes in the Ukrainian army, which is struggling to hold off Moscow's forces more than three years into Russia's invasion.

"Changes are needed, this is a mandatory issue," Zelensky said in his evening address.

Moscow's forces have been advancing across the front line for over a year and have been making inroads in Ukraine's Sumy region, which the Kremlin had not occupied since the start of the war.

Peace talks on ending the conflict have stalled in recent weeks and Kyiv's biggest ally, Washington, is now focusing its attention on the Middle East.

Russia says it is open to a peace settlement but Kyiv has accused Moscow of deliberately sabotaging talks to prolong the fighting.