Yevgenia Chirikova, leader of a campaign against the destruction of the Khimki forest in the Moscow region, was fined 2,300 rubles ($77) on Thursday by a Khimki court, Interfax reported.
Chirikova was punished for staging an unsanctioned rally on July 28 and disobeying a police order, a court official told Interfax, without elaborating.
Chirikova denied any wrongdoing.
Moscow region police briefly detained Chirikova on Wednesday in front of dozens of journalists as she spoke at a news conference in central Moscow. She was questioned about a July 28 attack on Khimki City Hall that is believed to have been staged by political activists, not environmentalists. Chirikova was camping out in the Khimki forest that day.