Ukrainian forces have lost between 10,000 and 13,000 soldiers in the war against Russia, according to a top advisor to President Volodymyr Zelenksyy.

In a Thursday night interview, Mykhailo Podolyak cited chief military officials when he revealed information that was detailed as "classified" by a Ukrainian armed forces spokesman earlier in the week. 

"We have official figures from the general staff, we have official figures from the top command, and they amount to between 10,000 and 12,500-13,000 killed," Podolyak told a Ukrainian news outlet.

Ukrainian national guard servicemen carry a bag containing the body of a Ukrainian soldier

Ukrainian national guard servicemen carry a bag containing the body of a Ukrainian soldier in an area near the border with Russia, in Kharkiv region, Ukraine, Monday, Sept. 19, 2022. (AP Photo/Leo Correa)

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The comments were not only a rare announcement, but the figures are likely far lower than Western estimates, as Chairman of the Joint Chiefs of Staff Mark Milley said last month both Ukraine and Russia have "probably" seen "well over 100,000" soldiers killed and wounded. 

A separate advisor to Zelenskyy, Oleksiy Arestovych, said in a Wednesday interview that Kyiv assessed the death toll in Russia’s ranks to be roughly seven times that of Ukraine’s, according to Reuters. 

Podolyak did not provide any estimates on the number of soldiers who had been injured, but said, "We are open in talking about the number of dead" and noted that more soldiers had been wounded than killed.

Kherson dog

Ukrainian soldiers carry supplies into the trenches on the front lines between Mykolaiv and Kherson in Ukraine, Tuesday, March 22, 2022.  (Photo by Salwan Georges/The Washington Post via Getty Images)

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Russia has remained silent on its reported dead and has not released any figures on its fallen soldiers in months. 

In late March, Moscow claimed it had lost over 1,300 soldiers in what it has dubbed its "special military operation" in Ukraine. However, after just one month of war, NATO officials had estimated that number was likely far higher and ranged between 7,000 and 15,000 Russian soldiers killed in Ukraine. 

The Ukrainian military has not confirmed the figures provided by Podolyak, and head of the armed forces last reported in August that 9,000 Ukrainian soldiers had reportedly been killed. 

Podolyak said in June that up to 200 soldiers were killed each day in the then four-month long war. 

Ukraine soldiers

Ukrainian soldiers in a truck on the Donbass frontline Donetsk, Ukraine, July 23, 2022.  (Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images)

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Civilian casualties in Ukraine remain largely unknown with the U.N. reporting some 17,000 casualties since the war began. 

The Office of the High Commissioner for Human Rights warned in its latest update Monday that it "believes that the actual figures are considerably higher."