(Reuters) - Scores of famous figures, including writers and actors, have signed an open letter urging Russian President Vladimir Putin to free opposition politician Alexei Navalny and to end what they called his torture in prison.
Nobel prize-winning writers Svetlana Alexievich, JM Coetzee, Herta Mueller, Orhan Pamuk, Olga Tokarczuk and Mario Vargas Llosa were among those who signed the appeal.
Navalny, a former lawyer who rose to prominence by lampooning Putin's elite and alleging vast corruption, is serving sentences totalling 11-1/2 years in a penal colony on charges including fraud which he says were trumped up to prevent him from challenging Putin, an idea the Kremlin rejects.
Russian authorities say Navalny and his supporters are extremists with links to the U.S. CIA intelligence agency intent on trying to destabilise Russia. They have outlawed his movement and Navalny himself is facing new charges that could add years to his prison sentence.
Navalny's supporters have grown increasingly worried about his health in recent weeks, saying they fear he could die in jail. They say he has suffered severe stomach pain and weight loss.
"He has been consistently returned to solitary confinement, (and) squeezed into a concrete cell the size of a dog kennel, with no ventilation," said the letter's signatories, who also included dancer Mikhail Baryshnikov, actors Jude Law and Benedict Cumberbatch, and writers Margaret Atwood, JK Rowling and Salman Rushdie.
"Visits from relatives and phone calls are forbidden, his attorney-client privileges have been cancelled. Despite running a fever, he is required to stand all day."
They said they were adding their voices to those of Russian doctors who had requested immediate medical attention for Navalny and to those of Russian lawyers and regional deputies demanding an end to what they called Navalny's "torture."
The Kremlin has declined to comment on Navalny's treatment or his state of health, saying it is a matter for the prison service which has said in the past that it is providing him with all necessary medical care.
Navalny earned admiration from Russia's disparate opposition for voluntarily returning to Russia in 2021 from Germany, where he had been treated for what Western laboratory tests showed was an attempt to poison him with a nerve agent in Siberia.
The Kremlin denied trying to kill him and said there was no evidence he was poisoned with a nerve agent.
(Reporting by Mark Trevelyan; Editing by Andrew Osborn)