Borys Romanchenko, 96, was killed late last week by Russian bombardment of his home in the besieged southeastern Ukrainian city of Kharkiv, authorities and officials announced Monday.

According to the Buchenwald and Mittelbau-Dora Memorials Foundation statement, Romanchenko was killed Friday when a Russian missile struck his apartment building as Kremlin forces continued their assault on the city.

"With horror, we have to report on Borys Romanchenko's violent death in the war in Ukraine," the foundation said, noting that Romanchenko served as the organization's international Buchenwald survivors committee's vice president in Ukrainian. "We lament the passing of a dear friend. We wish his son and granddaughter, who informed us of the tragic news, courage during these trying times."

Romanchenko was born in January 1926 in Ukraine's Bondari hamlet in the northeastern city of Sumy. In 1942, he became a victim of Nazi war crimes when compelled to work for the war machine. He was later detained at the notorious Buchenwald concentration camp in January 1943 following a failed escape attempt before being transferred to Peenemunde, where he assisted in constructing V2 rockets.

He was then transferred to the Mittelbau and Bergen-Belsen detention camps.

Russian President Vladimir Putin "managed to 'accomplish' what even Hitler couldn't," Ukraine's Defense Ministry declared following Romanchenko's death.

On Sunday, the United Nations reported that 925 people had been killed and another 1,496 injured in Ukraine since Russia's invasion began on Feb. 24. However, the actual figures are significantly higher.

At least 276 people, including 15 minors, were killed in Kharkiv Region.

The organization stated that Romanchenko worked "intensively" throughout his life to preserve the memory of Nazi war atrocities. In April 2015, at a ceremony commemorating the liberation of the former Buchenwald concentration camp 70 years before, Romanchenko repeated the Buchenwald survivors' oath.

"Build a new world of peace and freedom is our ideal," he is quoted as saying during the ceremony by the foundation.

"Borys Romanchenko's horrific deaths show how threatening the war in Ukraine is for concentration camp survivors," the charity stated.

Numerous internet commentators have expressed outrage that Russian forces murdered a victim of Nazi war crimes during a conflict Putin began on the pretense of denazifying Ukraine.

"Unspeakable crime," Ukraine's foreign minister Dmytro Kuleba tweeted in response to Romanchenko's killing. "Survived Hitler, murdered by Putin."