Oligarch Leonid Nevzlin publicly renounced his Russian citizenship on Tuesday.
The former oil tycoon fled Russia almost 20 years ago, claiming political persecution by Putin.
He joins a handful of oligarchs breaking ranks to speak out against the Ukraine war.
Leonid Nevzlin, an oligarch and former oil tycoon, renounced his Russian citizenship in a Facebook post on Tuesday.
"Russian citizenship has become a stamp of shame which I no longer want to wear. Enough is enough," Nevzlin wrote in the post. "I am against the war. I am against the occupation. I am against the genocide of the Ukrainian people."
"I cannot afford to be a citizen of a country that kills children of other countries," he continued.
But Nevzlin's "removal" of his citizenship is likely more symbolic than legally binding. Formal renunciation can take anywhere from six to 12 months, according to SRAS.
Nevzlin co-founded the Russian oil giant Yukos with fellow oligarch Mikhail Khodorkovsky, who spent nearly a decade in a Russian prison following charges of fraud and tax evasion in 2005.
During the Yukos investigation, Nevzlin fled to Israel, claiming he was the victim of political persecution.
In 2008, Nevzlin was sentenced to life in prison for murder and financial crimes, charges which he has repeatedly denied. Israel has refused Russia's extradition request.
"I was one of the first to be hit by Putin. He threw my friends in jails, and killed some of them," Nevzlin wrote. "Everything Putin touches dies."
Khodorkovsky, his former business partner, is also an outspoken critic of Russian President Vladimir Putin. Last week, he told CNN that Putin's invasion of Ukraine has "significantly reduced" his chances of remaining in power.
Steel tycoon Vladimir Lisin, who has avoided sanctions thus far, urged Putin to diplomatically end the war in a letter to his employees.
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