A left-wing critic of Russian President Vladimir Putin, Sergei Udaltsov, was sentenced to six years in a penal colony and convicted of justifying terrorism by a Moscow court on Thursday.

The sentence fell one year short of the seven years sought by the public prosecutor's office. Shortly before the verdict, Udaltsov declared he would begin an "indefinite hunger strike until death" if convicted.

After the judgment, he was quoted as saying by the opposition media outlet Meduza: "A shameful decision. All those who made it will be held accountable, I hope. Be damned, you dogs. I wish this for you with all my heart."

Udaltsov, whose wife Anastasia serves in the Russian State Duma for the Communist Party, supports Russia's war against Ukraine but is considered a Putin critic.

According to Meduza, Udaltsov's prosecution stems from his article "How Marxists Were Turned Into Terrorists."

In it, he voiced support for another group of Russian activists accused of forming a terrorist organization by the domestic intelligence service FSB.

The activists were sentenced earlier this month by a military court to prison terms between 16 and 22 years.

Udaltsov was a prominent leader of Russia's protest movement from 2011 to 2013, which opposed Putin's return to the presidency.

In 2014, Udaltsov was sentenced to four and a half years in prison on charges related to his role in organizing demonstrations against Putin, which turned into mass unrest. He was released in 2017.