Russia on Tuesday began hearing an appeal lodged by jailed Kremlin critic Alexei Navalny against a court decision to jail him for 19 years in a maximum security prison on extremism-linked charges.Navalny was Russia's loudest opposition voice over the last decade and galvanized huge anti-government rallies before he was jailed in 2021 on fraud charges that his allies at home and abroad said were punitive.A court in his prison near Moscow handed him a 19-year jail term last month, accusing him of having created an organization that undermined public security by carrying out "extremist activities."The 47-year-old trained lawyer threatened the Kremlin by establishing a network of political offices across the country and a corruption watchdog that brought credible graft allegations against political elites.He was jailed in 2021 after arriving in Moscow from Germany, where he had been recovering from a poisoning attack he blamed on the Kremlin.The ruling last month came a year and a half into Russia's Ukraine campaign, which brought with it an unprecedented crackdown on dissenting voices."You are being forced to surrender your Russia without a fight to a gang of traitors, thieves and scoundrels who have seized power.

Don't lose the will to resist," Navalny said in a statement of the ruling.Navalny, who has complained of a series of health complications — and undertook a weeks-long hunger strike — communicates with the outside world through his lawyers.Since the Kremlin launched large-scale hostilities in Ukraine last year, he has repeatedly spoken out against the military campaign.Russia has detained thousands of people including high-profile political activists for speaking out against the conflict and highlighting alleged Russian military atrocities.He is being held in the maximum security IK-6 penal colony, some 250 kilometers (155 miles) east of Moscow.But the court in August also ruled to send Navalny to a "special regime" colony, a maximum security facility reserved for dangerous criminals that will all but cut him off from the outside world.There are some 40 prisons across Russia, many in remote and isolated regions, in a network that campaigners say has not significantly reformed since the Soviet era.Navalny usually appears at court hearings via grainy video connections in prison uniforms looking considerably leaner than when he addressed thousands of supporters at rallies in Moscow and Russia's regions.Allies say his health has taken a further hit in recent months, during which he has been in and out of solitary confinement.Ahead of the appeal, prison wardens placed Navalny in a detention cell for the 20th time, his team said.Navalny also remains a fringe figure for a large portion of Russian society, who back the Kremlin's official portrayal of him as a Western stooge and convicted criminal.Most of his allies have been forced into exile since Russia launched its full-scale Ukraine offensive last February.

Many of those who remained have been put on trial.Lilia Chanysheva, Navalny's ally in the central Bashkortostan Republic, was handed seven and a half years in prison this summer.Another ally in the Siberian city of Tomsk, Ksenia Fadeyeva, is currently on trial, accused of creating an extremist organization.