The imprisoned Kremlin critic Alexei Navalny said he was in a punishment cell for three days for minor violations of prison rules.
He tweeted Monday through his lawyers that he had been fined for regularly failing to button the top button of his prison uniform.
He also tried to persuade fellow prisoners to set up a union.
“The solitary confinement cell is a 2.5 x 3 meter concrete kennel.
It's unbearable in there most of the time because it's cold and damp.
There is water on the floor,” wrote President Vladimir Putin's opponent, adding ironically: “I have the beach version – it's very hot there and there's almost no air circulation.” The window is tiny, there's no ventilation.
"At night you lie there and feel like a fish out of water.
At five in the morning they take away your mattress and pillow (...) and lift up your bunk.
At 9:00 p.m. the bunk is lowered again and the mattress is returned.
There is an iron table, an iron bench, a sink, a hole in the floor, and two cameras on the ceiling.”
Navalny is reportedly serving his sentence on probation violations, fraud and contempt of court in the IK-6 penal colony in Melekhovo, some 250 km east of Moscow.
Authorities in Russia describe Navalny and his comrades-in-arms as enemies of the state who wanted to destabilize Russia with the support of the West.
Navalny was arrested in January 2021 when he returned home from Germany and convicted of violating the conditions of probation.
He collapsed on a domestic Russian flight in August 2020.
First he was treated in Russia, then transferred to the Berlin Charité.
There, poisoning with a nerve agent was determined.
The government in Moscow has denied allegations that Russian authorities tried to kill the Putin opponent.