A still from video footage shows Russian opposition leader Alexei Navalny accused of disregarding the terms of a suspended sentence for embezzlement during the delivery of a court verdict in Moscow, Russia, on February 2, 2021.

Simonovsky District Court | via Reuters

WASHINGTON – The Biden government said Wednesday it was concerned about reports that the health of Russian opposition leader Alexei Navalny had deteriorated since his arrest and reiterated calls for his immediate release.

Navalny, who was arrested at a Moscow airport in January, is on hunger strike to force prison guards to access outside medical care because of pain in his back and legs. A Navalny lawyer said he had two spinal hernias, AP reported.

The Kremlin has refused to comment on his health.

“We urge the Russian authorities to take all necessary measures to ensure his safety and health. While he is in detention, the Russian government is responsible for his health and well-being,” said White House press secretary Jen Psaki , on Wednesday during a briefing.

“We stand with like-minded allies and partners to demand his immediate release and an end to the persecution of his supporters,” she said, adding that Navalny’s detention was “politically motivated” and a “gross injustice”.

Human rights group Amnesty International told Reuters on Wednesday that Russian authorities were trying to slowly kill Navalny while he was in detention.

Navalny, a leading critic of Russian President Vladimir Putin, flew from Berlin to Russia in January, where he recovered for almost six months from nerve agent poisoning that occurred in August. He was arrested at passport control and later sentenced to more than two years in prison.

Last summer, Navalny was medically evacuated to Germany from a Russian hospital after falling ill after reports that something had been added to his tea. Russian doctors treating Navalny denied the Kremlin critic had been poisoned and blamed his comatose condition for low blood sugar levels.

In September the German government announced that the 44-year-old Russian dissident had been poisoned by a chemical agent for nerves and described the toxicological report as “clear evidence”. The military-grade nerve agent belonged to the von Novichok family developed by the Soviet Union. Toxicological tests carried out in France and Sweden came to the same conclusion.

The Kremlin has repeatedly denied playing a role in Navalny’s poisoning.

Last month, the United States sanctioned seven members of the Russian government for alleged poisoning and subsequent imprisonment of Navalny. The sanctions are the first to target Moscow under the leadership of President Joe Biden. The Trump administration has taken no action against Russia because of the situation in Navalny.

State Secretary Antony Blinken wrote in a separate statement that the sanctions would send “a clear signal” to Russia that the use of chemical weapons and human rights violations are having grave consequences.

“Any use of chemical weapons is unacceptable and violates international standards,” wrote Blinken.