[Source: CNN]

Imprisoned Russian dissident Alexey Navalny has been transferred into a solitary prison cell, according to tweets from himself and his staff, in what he described as a move designed to “shut me up.”

Navalny, a prominent critic of Russian President Vladimir Putin, explained what happened in a Thursday Twitter thread: “Congratulations, I’ve moved up one more level in the hierarchy of prison offenders,” Navalny wrote with irony, adding that prison officials moved him to a cramped “cell-type room.”

Cell-type rooms are used as punishment or to separate the most dangerous offenders in the Russian penitentiary system. Inmates in Russian penal colonies are more typically housed in barracks instead of cells according to a report by Poland-based think tank the Centre for Eastern Studies (OSW).

In his isolation, Navalny said that he is allowed just two books and can use prison commissary, “albeit with a very limited budget.”

But the “real indescribable bestiality, very characteristic of the Kremlin, which manually controls my entire incarceration,” is the blocking of visits, he said. His parents, children and wife were due to visit, but he will no longer get to see them, Navalny wrote.

“Alexey Navalny was transferred to a cell-type room. It’s like a punishment cell, only not for 15 days, but forever,” wrote his spokesperson Kira Yarmysh on Twitter.

According to the Russian penal code, detention in a cell-type room cannot exceed six months.

CNN has reached out to Russian penitentiary services for comment.