Pulitzer Prize-winning Russian journalist and opposition activist Vladimir Kara-Murza has been transferred to a prison hospital while serving out a 25-year sentence for criticizing his country’s invasion of Ukraine, his wife announced via social media on Friday.

His wife, Evgenia Kara-Murza, shared via X that her husband had been transferred from his maximum security prison in Siberia to a prison-run hospital. His lawyers were denied access to him on Friday without a clear explanation, and will now have to wait until next week to check on their client’s welfare due to prison hospital policy, the activist’s wife wrote via X. She added that Kara-Murza suffers from polyneuropathy as a result of two assassination attempts — a condition that should exempt him from serving a prison sentence under Russian law.

The Free Russia Foundation, an organization advocating for democracy in Russia, also released a statement calling on Russian authorities to immediately allow Kara-Murza’s lawyers to see him, as required by law. It also called on the international community to advocate for his rights:

[The foundation] urges the international community to join in pressuring the Russian government to respect Kara-Murza’s rights, provide transparency regarding his situation, and grant his lawyers immediate access. We call on the Russian authorities to take swift action to ensure that Kara-Murza receives the necessary medical care and that his lawyers are allowed unhindered access to assess his condition

In April 2023, Kara-Murza was sentenced to 25 years in prison by a Russian court on a range of charges including treason and the dissemination of false information. These charges stemmed from his outspoken criticism of Russia’s involvement in the Ukraine conflict, marking the longest sentence handed down since the conflict began. Following the court decision, he was transferred over a three-week period to a high-security penal colony located in Omsk, Siberia.

Strict legislation curbing speech about Russia’s invasion of Ukraine has led to a spike in arrests of opposition figures. Earlier this year, Russia’s most prominent opposition figure — Alexei Navalny — died while serving a sentence in an Arctic prison colony.

Speaking about Russia’s spate of censorship legislation, UN officials stated last year:

The law has no other objective than silencing critical expression in relation to the war in Ukraine. The legislation is a drastic step in a long string of measures over the years restricting freedom of expression and media freedom, and further shrinking civic space in the Russian Federation