Imprisoned Russian opposition leader Alexei Navalny said Wednesday he was being moved to a “cell-type facility” within a Russian penal colony that would likely extend his time without visits to more than a year, as his supporters continue to raise alarms about his declining physical condition.

“Even maniacs and serial killers serving life sentences have the right to receive a visit, but I don’t,” Navalny wrote on Twitter. “Well, hardships make one tougher, though I don’t understand why this should apply to my children too.”

Navalny said he would spend six months, the maximum possible term under Russian law, in the new facility and that he would be denied visits, as he has for the prior eight months.

The move is an unmistakable effort to destroy Navalny’s health by any means, his lawyer, Vadim Kobzev, said on Twitter on Wednesday. He accused prison officials of deliberately infecting Navalny with an illness and then administering inappropriate treatment. Navalny was experiencing sharp stomach pains and had lost over 15 pounds, Kobzev reported.

One of President Vladimir Putin’s most prominent critics, Navalny has been jailed since he returned to Russia in 2021, after recovering in Germany from an assassination attempt that Western officials say was carried out by the Kremlin. He has spent much of his time in prison in so-called punishment cells.