The extension in sentence came after Alexey Navalny was found guilty of additional embezzlement and contempt of court charges.
A Russian court has found jailed Kremlin critic Alexey Navalny guilty of additional charges and extended his sentence to nine years in a higher security prison as Moscow seeks to wipe out remaining pockets of dissent.
Following the verdict on Tuesday, President Vladimir Putin's most vocal domestic critic who has been behind bars for more than a year said the Russian leader was afraid of the truth.
"Putin is afraid of the truth, I have always said this. Fighting censorship, relaying the truth to the people of Russia always remained our priority," the 45-year-old opposition politician said in an Instagram post.
Found guilty of additional embezzlement and contempt of court charges, Navalny also urged Russians to resist "these war criminals" on a Twitter post.
Navalny has denied the charges against him, saying they were punishment for challenging 69-year-old Putin. He will serve his new sentence in a strict-regime penal colony, which will place him in much harsher conditions.
1/10— Alexey Navalny (@navalny) March 22, 2022
9 years of strict regime.
My space flight is taking a bit longer than expected - the ship is caught in a time loop.
It occurred to me that my role in this saga is similar to that guy from Interstellar.
Another eight years
Investigators accused Navalny of stealing for personal use several million dollars' worth of donations that were given to his political organisations.
The prosecutors had last week called for Navalny's sentence to be extended to 13 years as well as for his transfer to a strict-regime penal colony.
Last year the opposition leader was sentenced to two and a half years for violating parole for old fraud charges while recovering from a poison attack with Novichok nerve agent that he blames on the Kremlin.
Navalny's defence team said the new sentence replaces the one he is currently serving, meaning that he will not be freed for another eight years, instead of a year and a half.
He will also have to pay a fine of $11,500 (1.2 million rubles) and upon his release he will have to abide by various restrictions on his movement and activities for a further 1.5 years.
US State Department spokesman Ned Price condemned the verdict as a "sham ruling" and the "latest in a series of attempts to silence Navalny".
The EU's foreign policy chief Josep Borrell called for his "immediate and unconditional release".
"The world is watching, and lamenting the disappearance of freedom and the repression of political opposition in Russia," the Canadian foreign ministry tweeted.
Amnesty International's director for Eastern Europe and Central Asia, Marie Struthers, called the sentence predictable but "shocking."