Navalny's life is Putin's 'personal' responsibility, say Russian politicians

Moscow (CNN) Nearly a dozen Russian politicians have published an open letter to President Vladimir Putin, saying that he was personally responsible for the life of Kremlin critic Alexey Navalny, who has been on a hunger strike in a penal colony in the Russian city of Pokrov.

"The state of health of political prisoner Alexey Navalny threatens his life," said the letter, signed by 11 politicians representing several regional parliaments, as they demanded an independent doctor is immediately allowed to visit Navalny.

The opposition figure went on a hunger strike on March 31, demanding "proper medical care" and to be examined by an independent doctor -- something his team claims he has been unable to get in the penal colony in Pokrov.

His allies have been raising concerns about the jailed Kremlin critic's health, saying Navalny "is dying" and his doctors said medical tests showed he's at growing risk of renal failure and heart problems. CNN is unable to independently verify the state of Navalny's health.

"We regard what is happening in relation to Navalny as an attempt on the life of a politician, committed out of personal and political hatred," the letter, which is open for Russian citizens to sign, said. It was first shared and circulated late Saturday night.