Ilya Ponomaryov, a former member of the Russian parliament’s lower chamber, the State Duma, has been added to the Interior Ministry's list of terrorists and extremists.
Ponomaryov's name appeared in the list on January 25 with a mark, meaning that the ministry has materials alleging that Ponomaryov is linked to terrorism.
Ponomaryov, 47, was the only lawmaker in the State Duma who voted against Russia's 2014 seizure of Crimea from Ukraine.
He fled Russia for the United States in 2014 and later moved to Ukraine, where he has lived since then.
In 2016, his immunity as a lawmaker was stripped in Russia in absentia.
After Moscow launched its unprovoked full-scale invasion of Ukraine in February last year, Ponomaryov joined Ukraine's territorial defense group and created online resources calling on Russian citizens to take up armed resistance against Russian authorities.
In late-August, a court in Moscow issued an arrest warrant for Ponomaryov on a charge of discrediting Russian armed forces. The charge stemmed from his interview to the Forum of a Free Russia YouTube channel, in which he condemned the war in Ukraine.
In December, police searched the homes of owners of various Telegram channels and local lawmakers linked to Ponomaryov in seven Russian cities.
In October, Ponomaryov was labeled as a foreign agent.
Russia has used its foreign agent laws since 2012 to label and punish critics of government policies. The legislation has also been increasingly used by officials to shutter civil society and media groups in Russia since Moscow's invasion of Ukraine began in February.