Ukraine's President Volodymyr Zelensky on Tuesday said he had revoked the citizenship of Viktor Medvedchuk, once seen as Russian leader Vladimir Putin's top ally in Kyiv and accused of high treason.
Medvedchuk, a former Ukrainian lawmaker who was handed over to Russia in a prisoner exchange last September, was stripped of his citizenship along with three others, Zelensky said in his daily address.
Based on materials prepared by Ukraine's security and state migration services and in accordance with the constitution, "I have decided to terminate the citizenship of four persons," Zelensky said.
He said the actions were appropriate for those who "choose to serve not the people of Ukraine, but the murderers who came to Ukraine."
Zelensky also warned that these would not be "the last such decisions."
Medvedchuk was one of more than 50 prisoners handed over to Russia in September in exchange for 215 Ukrainian imprisoned soldiers.
The swap was the biggest exchange between the warring sides since the start of Russia's invasion in February 2022.
The Ukrainian tycoon was captured in April last year by Ukraine's special services, after fleeing home arrest when Russia invaded.
The super-rich powerbroker — once dubbed the "dark prince" of Ukrainian politics — was accused of high treason and attempting to steal natural resources from Russia-annexed Crimea and of handing Ukrainian military secrets to Moscow.
The others to lose their Ukrainian citizenship include Andriy Derkach — an alleged Russian agent and wealthy former member of the Ukraine parliament.
In June Derkach was accused by the Ukrainian government of supporting Russia's invasion and a warrant was issued for his arrest.
The U.S. Justice Department has said Derkach also took part in an effort to smear President Joe Biden over his son Hunter Biden's Ukraine ties.
Another to lose their Ukrainian citizenship, Taras Kozak, has been accused by the United States of being involved in operations by Russia's FSB intelligence service to undermine the Ukrainian government and economy.
Renat Kuzmin, also a Ukrainian politician suspected of links with Russia, was the fourth man Zelensky said would be stripped of his citizenship.