Jailed Putin critic Alexei Navalny could 'die at any minute,' doctors warn

Alexei Navalny attends a court hearing in Moscow Russia

The daughter of hunger-striking Kremlin critic Alexei Navalny called on Russian authorities on Sunday to allow a doctor to treat her father in prison, a day after a group of medical professionals warned he is at risk of kidney failure. Navalny blames the poisoning on the Kremlin.

Joe Biden said Alexei Navalny was in a "totally unfair" situation.

Navalny's personal doctor Anastasia Vasilyeva said Navalny "can die any minute", in a post on Facebook on Saturday, pointing to high potassium levels.

Navalny, who has been complaining about severe back and leg pain, went on a hunger strike at the end of March, after being denied a visit by a doctor of his own choice.

She said he should be moved into an intensive care station, adding "fatal arrhythmia can develop any minute".

He was arrested in January when he returned to Russian Federation from Germany, where he had been recovering from a nerve agent poisoning attack he blamed on Putin.

"This means both impaired renal function and that serious heart rhythm problems can happen any minute", it explained.

Having blood potassium levels higher than 6.0 mmol (millimole) per liter usually requires immediate treatment.

Last week, Russian Foreign Ministry's spokeswoman, Maria Zakharova, said that the United States is making up "stories" about Navalny's detention conditions while the USA itself continues to violate the rights of prisoners.

"If the treatment does not start, he will die in the next few days", opposition spokeswoman Keira Ermic said on Twitter.

More than 70 personalities, including Jude Law, Vanessa Redgrave and Benedict Cumberbatch, demanded in an article published Friday evening in the French newspaper "Le Monde" that necessary medical care be secured for Navalny. Police arrested more than 10,000 people during nationwide protests in January calling for Navalny to be freed.

Yarmysh on Saturday urged more Russians to sign up, saying that a big rally could help save Navalny's life.

Earlier this week, Navalny's wife Yulia, who visited him in the penal colony, said her husband now weighed 168 pounds - down almost 20 pounds since starting his hunger strike.

On Friday, Russian prosecutors asked a court to designate Navalny's Anti-Corruption Foundation and the network of his regional offices as "extremist" in a move that would outlaw them in Russia and could result in jail time for their members.