Kremlin critic Alexey Navalny is being held in a prison camp in Russia's Vladimir region northeast of Moscow known for its strict control of inmates, a message posted on the opposition politician's Instagram account confirmed on Monday.
Navalny's precise location had been unknown after his legal team said last week that he had been moved from the nearby Kolchugino jail and that they had not been told where he was being taken.
On Monday, Navalny confirmed he was fine and being held at the IK-2 corrective penal colony in the town of Pokrov, about 100 km (60 miles) east of Moscow.
"Hi everyone from 'Heightened control sector A'," Navalny said in a message posted online shortly after his lawyers visited him at the facility.
"I have to admit that the Russian prison system has managed to surprise me. I never imagined that it was possible to build a real concentration camp 100 kilometers from Moscow."
The post was accompanied by a picture of Navalny sat on a sofa with his hair cropped close to his head.
Navalny, 44, one of President Vladimir Putin's most prominent critics, was jailed earlier this year for parole violations in a decision that the West has condemned as politically motivated.
He is due to serve out a two-and-a-half year sentence and is only able to communicate with the outside world via his lawyers.
The Instagram post said that swearing was banned at the facility and that the ban was widely observed by fellow inmates who seemed scared to turn their heads twice.
He said he had not seen any prison violence or suggestion of it himself but could believe stories he had heard about past cases of violence.
"There are video cameras everywhere, they keep watch on everyone and make reports for the slightest infractions. I think someone high up has read 1984 by Orwell," he said.
He said he was woken up every hour during the night because he had been deemed a flight risk.
"But if you regard everything with humor, you can live here. So on the whole everything is fine with me," he said.
Navalny returned to Russia in January from Germany where he had been recuperating from being poisoned with what many Western nations said was a nerve agent. The Kremlin has denied involvement in his illness and questioned if he was poisoned.
Western countries have called for Navalny's release, and the United States and European Union have imposed sanctions against Russian officials over the case.
