Jailed Russian opposition leader Aleksei Navalny's health has rapidly deteriorated and he could suffer cardiac arrest "any minute," according to doctors demanding immediate access to the prominent Kremlin critic.
The plea came from Navalny's personal doctor, Anastasia Vasilyeva, and three other doctors, including a cardiologist, in a letter to Russia's Federal Prison Service officials that was posted to Vasilyeva's Twitter account on April 17.
SEE ALSO: Hunger-Striking Navalny Says Prison Staff Threatened To Force-Feed HimNavalny, 44, announced a hunger strike at the end of last month in protest at what he said was the refusal of prison authorities to allow him to receive proper medical care for acute back and leg pain.
The opposition leader said on April 16 that prison authorities were threatening to put him in a straightjacket to force-feed him.
The doctors' statement said that blood tests showed that Navalny's potassium count had reached a "critical level."
"This means both impaired renal function and that serious heart rhythm problems can happen any minute," the letter said.
SEE ALSO: Amnesty International Decries Russian Prosecutor's Call To Label Navalny Organizations As 'Extremist'Navalny was arrested in January on his arrival from Germany where he was treated for poisoning in Siberia with what was defined by European labs as a nerve agent in August last year. He has accused President Vladimir Putin of ordering the poisoning, which Kremlin has denied.
A Moscow court sentenced the opposition leader in February to 2 1/2 years in prison on charges he says were politically motivated.
Kira Yarmysh, Navalny's spokeswoman, wrote on Facebook on April 17 that the situation reminded her of the helplessness she felt after his poisoning.
"Now Aleksei is dying. In his condition, it is a matter of days. And over the weekend, lawyers just can't get to him, and no one knows what will happen on Monday," she wrote.
Yarmysh wrote that she did not want mass protests expected to take place in the coming weeks to demand Navalny's release to attract large crowds only because he had died, and called on supporters to sign on to an online petition indicating they will attend in advance.
Saying that Putin only reacts to street protests, Yarmysh wrote, "This rally is no longer Navalny's chance for freedom, it is a condition for his life."