Russia's Ministry of Justice late Friday designated one of the country's most popular fiction writers a "foreign agent" because of his opposition to Moscow's war in Ukraine.

The historical detective stories of Boris Akunin, the pen name of Georgian-born Grigori Chkhartishvili, used to be bestsellers in Russia before the authorities turned on him for what they said were his unacceptable anti-Russian views.

The justice ministry cited Chkhartishvili's opposition to what Moscow calls its "special military operation" in Ukraine and accused him of distributing false and negative information about Russia and of helping raise money for the Ukrainian military.

The 67-year-old author lives in Britain.

The "foreign agent" designation carries a negative Soviet-era connotation and obliges people to identify as foreign agents on social media and in other publications and exposes them to burdensome financial reporting requirements.

Other writers and cultural figures who have angered the authorities by speaking out against the Ukraine war have received the same designation.

Books by "Boris Akunin" — best known for his fictional Tsarist-era detective Erast Fandorin — have already been removed from sale in Russia after the authorities added him to a list of people they accuse of being involved in terrorism or extremism.

Chkhartishvili, who makes no secret of his opposition to Russia's war in Ukraine, made light of his foreign agent designation in a social media post.

"They are writing that I have been declared a foreign agent today. Me, a terrorist and extremist?! I feel like Bin Laden who has been given a ticket for parking illegally," he wrote.