Jailed Russian opposition politician Alexei Navalny says he has been moved to a small, isolated cell and deprived of family visits, his team announced on social media.
Navalny said he had been placed in a "cramped cell" used for prisoners accused of bad behavior, adding: "Congratulate me!"
Under the toughened detention conditions, he is only allowed two books and deprived of long-stay family visits, he said.
Four days before a visit, he was informed he was being transferred to a type of cell where "long-stay visits don't exist," Navalny said, adding that he has not seen his wife, children or parents for several months.
Long-stay visits allow Russian penal colony inmates to spend up to three days with their relatives on the grounds of the facility where they are held.
"They are doing it to shut me up. That means that my main obligation is what? Exactly! Not to be afraid and not to be quiet," he added.
Navalny, President Vladimir Putin's most vocal domestic critic, is serving nine years in jail on a series of charges he says are politically motivated.
He was sentenced to nine years in prison for fraud in March.
The 46-year-old was arrested in January 2021 upon returning from Germany, where he recovered from a poison attack that almost killed him, which he blames on the Kremlin.
He has been communicating with the public and also sending messages through his legal team since he was detained.