A Russian court on Wednesday handed a two-year suspended sentence to Moscow city councillor and opposition activist Yulia Galyamina for repeatedly violating rules on public gatherings.

"Found guilty. Two-year suspended sentence," Galyamina wrote on Twitter. 

In mid-July Galyamina, 47, and her allies staged a protest against President Vladimir Putin's controversial changes to the constitution that could see the longtime Russian leader stay in power until 2036.

The deputy, who is also a university professor, was detained after the event and the same month investigators opened a criminal case against her for allegedly repeatedly violating rules on public assembly.

Russian prosecutors had demanded a three-year jail term, and Wednesday's verdict was seen by many as relatively lenient.

Ahead of the sentencing dozens of Galyamina's supporters gathered outside Moscow's Tverskoi district court in sub-zero temperatures, with some shouting "Set her free!"

More than 150,000 people also signed a petition demanding that she be set free and saying authorities were prosecuting the city deputy for her political activism.

In July, Putin had overseen a deeply controversial seven-day vote amending the constitution that included populist measures such as an effective ban on gay marriage.

Galyamina and her allies gathered some 40,000 signatures against the reform and demanded that the Supreme Court annul the vote results. 

The court threw out the case.

The opposition lawmaker had said she plans to run in parliament elections next year. 

"Galyamina's prosecution for collecting the signatures is a politically motivated case -- it's directly linked to her political work and potential," said the petition in her support.

Kremlin critics accuse Russian authorities of ramping up pressure on the opposition with new repressive legislation and intimidation campaigns.