China's foreign ministry declined to comment on Saturday on the death of Russian opposition leader Alexei Navalny, describing it as "Russia's internal affair".

"This is Russia's internal affair. I will not comment," the Chinese Foreign Ministry's Spokesperson's Office said in response to a question from AFP.

Navalny, the Kremlin's most prominent critic, died on Friday in an Arctic prison, Russian officials said, a month before an election poised to extend President Vladimir Putin's hold on power.

His death after three years in detention and a poisoning that he blamed on the Kremlin, deprives Russia's opposition of its figurehead at a time of intense repression and Moscow's campaign in Ukraine.

Beijing and Moscow are staunch allies and have strengthened their relationship even as Western countries have turned their backs on Russia over its military invasion of neighbouring Ukraine.

Both sides have also made much of the personal relationship between the two leaders, and China's president Xi Jinping has referred to his Russian counterpart Putin as his "good friend".

Dissidents and some Western leaders placed the blame squarely on Putin and his government for the 47-year-old's death, which followed months of deteriorating health in harsh detention conditions.

AFP

Alexei Navalny inside a defendant dock during the announcement of a court verdict in Moscow, February 2, 2021. via Press service of Simonovsky District Court

China declines comment on Navalny death, 'Russia's internal affair'