A Russian court on Tuesday banned a 19-year-old anti-Kremlin activist from leaving her town near Moscow for more than two years after finding her guilty of vandalism, a sentence her supporters said was unduly harsh.

Olga Misik, a journalism student in Moscow, became an anti-government protest symbol as a 17-year-old, when she sat down on the pavement in front of a row of riot police during a 2019 protest and read the constitution aloud.

Moscow's Mirovoy Court sentenced Misik, sometimes known as "the girl with the constitution", to two years and two months of restricted liberty for splashing paint on a booth outside the Prosecutor General's office to protest a state crackdown against activists, she said.

The court ruling also means she cannot leave her home at night.

The court, which did not immediately respond to a request for comment, also sentenced Igor Basharimov and Ivan Vorobyovsky, who took part in the protest with Misik, to similar restrictions. Their defence said it would appeal the ruling.

-All of this for a dribble of paint at the entrance of the Prosecutor General's office that was washed off that same morning- opposition politician Dmitry Gudkov said.

Police have stepped up their crackdown on opposition activists in the wake of protests calling for the release of jailed Kremlin critic Alexei Navalny. Russian authorities had warned that the protests were illegal and those taking part could face charges.