Russian opposition leader Alexei Navalny has announced a hunger strike at the penal colony where he is held, to demand proper medical treatment.
He has complained on Instagram of not receiving medical help for back pain and problems with his right leg, as well as being deprived of sleep.
Navalny, 44, returned home from Germany in January after treatment for a nerve agent attack in Siberia in August.
He was taken into custody immediately and then given a jail sentence.
He is currently being detained at the IK-2 corrective penal colony 100 km (60 miles) east of Moscow and has accused the guards there of denying him proper treatment for his ailments.
Russia’s federal penitentiary service has rejected his complaint, insisting he had “all the necessary medical assistance in accordance with his medical indications”.
A fierce critic of President Vladimir Putin, Navalny was given a two-year and eight month sentence last month for violating the probation terms of an embezzlement case.
The conviction was widely seen as politically motivated and the European Court of Human Rights said he should be freed because of the risk to his life. Kremlin spokesman Dmitry Peskov said this week that Navalny was “responsible for his deeds under the law” and no different from any other Russian.