The European Union has strongly condemned the "outrageously harsh" sentencing of Kremlin critic Vladimir Kara-Murza to 25 years in prison, it said in a statement on Monday.

"Today’s outrageously harsh court decision clearly demonstrates yet again the political misuse of judiciary in order to pressure activists, human rights defenders and any voices opposing Russia’s illegitimate war of aggression against Ukraine," the EU statement said."The European Union stands in solidarity with all those Russians who are prosecuted, imprisoned or intimidated for fighting for human rights, speaking the truth and criticising the regime," it continued.

"We call on Russia to immediately and unconditionally release all those imprisoned for politically motivated charges," the EU said.

Western nations, including the United States, United Kingdom and Germany, along with human rights groups, have condemned Kara-Murza's sentencing.

He will appeal the sentence, his lawyer told CNN on Monday.

The Kremlin has declined to comment on the sentencing.

Kara-Murza was initially detained one year ago, hours after an interview with CNN in which he criticized Russian President Vladimir Putin's "regime of murderers."