The opposition leader’s campaign filed five applications for meet and greets with supporters on Friday, Saturday and Sunday in central locations including Revolution Square and Pushkin Square, with a total of 15,000 people anticipated.

But the mayor’s office refused, saying “there are no grounds” for holding such meetings under Russian law, the RBC news outlet reported.

The campaign also unsuccessfully submitted notices for pickets on the same dates, saying their purpose was “to inform citizens about Navalny’s opinion on the social economic situation in Russia and the necessary measures to counter corruption.”

Navalny’s blog post Wednesday urged his Moscow supporters to come “to any point along Tverskoy Boulevard from Pushkin to Manezh” squares, because the city authorities had rejected their previous request for a gathering “without providing an alternative space.”

“I think in the given situation, the prosecutor’s office will issue a warning,“Vasily Oleynik, a Moscow city official was cited by RBC as saying, adding “in the event of any disturbance of the peace, law-enforcers may prosecute violators.”

In St. Petersburg, Navalny campaigners also applied to hold rallies. But Ivan Krasnov, a city official told RBC said the action was not approved. “Any attempt to hold it will be deemed illegal,” he warned.