MOSCOW - Russian prison officials said Monday that hunger-striking, jailed opposition politician Alexey Navalny has been transferred to a prison hospital.
"At the present time, Navalny's health is assessed as satisfactory, and he is being examined daily by a physician," the federal penitentiary service said in a statement. "With the patient's consent, he was prescribed vitamin therapy."
Navalny's allies did not have an immediate response to the opposition leader's move to the hospital at a high security prison east of Moscow.
Earlier Monday, a Navalny ally had warned that there was no hope of receiving good news about his health.
Lyubov Sobol told Ekho Moskvy radio on Monday that Navalny's allies expect to receive an update about the politician's health status later in the day, according to the Reuters news agency.
Allies of Navalny announced nationwide protests after the opposition figure's family and personal doctors released blood analysis results that suggested he was at high risk of cardiac arrest or kidney failure.
The planned protests are scheduled for Wednesday and fall on the same day that President Vladimir Putin delivers his annual State of the Nation address from just outside the Kremlin - all but ensuring a tense standoff between Navalny supporters and police in the capital, Moscow.
Over the weekend, Navalny's doctors said that blood tests - provided by the opposition figure's lawyers to his family - showed his potassium count had reached a "critical level."
"This means both impaired renal function and that serious heart rhythm problems can happen any minute," said the letter, which was signed by Navalny's personal physician, Anastasia Vasilyeva, and three other doctors.
"If they don't start treating Navalny, he will die within days," warned his other physician, Alexander Polupan.
FILE - A still image from CCTV footage published by Life.Ru shows what is said to be Alexey Navalny speaking with a prison guard at the IK-2 corrective penal colony in the town of Pokrov, Russia, in this image released Apr. 2, 2021.
Navalny, 44, is currently on the third week of a hunger strike in an effort to gain access to medical treatment. He is serving a 2½-year sentence in a prison 100 kilometers from Moscow.
On Friday, the opposition leader said prison authorities were threatening to force-feed him.
Previously, he has detailed efforts by prison authorities to lure him out of his hunger strike - including slipping candy into his pockets and grilling chicken in the prison barracks.
For several weeks, Navalny has described acute pain in his back that caused a loss of sensation in his legs and arms. Through his lawyers, he has also complained of a severe cough and dizziness.
Navalny maintains that his ailments are linked to an August 2020 poisoning attack with a military-grade nerve agent that nearly took his life, and that he and Western governments blame on the Russian government.
The Kremlin has denied any involvement but also refused to investigate the incident - saying that there is no definitive proof Navalny was ever poisoned.
The government has also deployed state media to Navalny's prison to film reports that portray conditions at the penal colony as near ideal, and Navalny as seeking special treatment by faking his symptoms.
Yet the latest blood results suggested Navalny's very survival was at stake, said his press secretary, Kira Yarmysh, on social media.
A poisoned affair
Navalny was sentenced to prison in February for violating parole obligations dating back to a 2014 fraud conviction he argues was politically motivated to disqualify him from taking part in Russia's political space.
The parole violation charges appeared only after Navalny had spent months recovering in a German hospital from the poison attack. The action was widely seen as an effort by the Kremlin to strongly encourage the opposition figure to remain in exile.
Instead, Navalny announced he was returning home to Moscow, where he was promptly detained at the airport by police in January.
Following his conviction, it later emerged he would be serving out his sentence at the IK-2 facility in the town of Pokrov, a high-security prison known for imposing a strict regime of psychological pressure on prisoners, say former inmates.
The United States and its European allies have demanded Navalny's release and issued sanctions against top Russian government officials and state entities involved.
The Kremlin has rebuffed Western demands and sanctions as attempts to interfere in Russia's internal affairs.
Fern Robinson contributed to this report.