The Kremlin has warned supporters of jailed opposition leader Aleksei Navalny not to hold rallies without permission from the authorities, saying that violators will be prosecuted.
"Public calls for unsanctioned rallies and meetings are illegal...and therefore organizers of such events will be prosecuted," President Vladimir Putin's spokesman, Dmitry Peskov, told reporters in Moscow on October 3.
The warning came as supporters of Navalny, who is trying to get on the ballot in a presidential election in March, called for nationwide protests on October 7 -- Putin's 65th birthday.
A Moscow court ordered Navalny held in custody for 20 days on October 2, preventing him from attending what was initially expected to be an October 7 rally solely in St. Petersburg, Putin's hometown.
"I call on all of you to continue to take part in the election campaign and in protest actions -- not only in [St. Petersburg] but across the entire country," Navalny said after the court hearing, according to his campaign website.
He called his third incarceration this year a "birthday present" given to Putin by Putin, while human rights group Amnesty International described it as "yet further evidence of the Russian authorities' relentless stranglehold on civil society."
Navalny is an outspoken critic of Putin, who has held power as prime minister or president since 1999 and expected to seek and secure a new six-year Kremlin term in the March 18, 2018, election.
The 41-year-old lawyer, who has produced numerous reports alleging corruption among key Putin allies, has opened more than 60 campaign offices and held rallies nationwide since announcing in December that he plans to seek he presidency.
In June, however, the Central Election Commission said that Navalny was ineligible to run for public office because of a financial-crimes conviction in a case that he contests was fabricated by the Kremlin for political reasons.
Navalny and some of his campaign workers and supporters have faced attacks and other forms of pressure in recent months.
Navalny was detained by police outside his Moscow home on September 29 as he left to catch a train for the Volga River city of Nizhny Novgorod, where he had organized a rally that evening.
He and his campaign chief, Leonid Volkov, were found guilty of calling for an unsanctioned rally in Nizhny Novgorod and sentenced to 20 days in jail each by different courts in Moscow on October 2.
Navalny and his supporters contended that organizers had received permission for the rally.
Volkov has announced a hunger strike protesting his sentence.
Kremlin opponents and human rights activists say the government frequently violates the constitutional right to free assembly when it withholds permission for demonstrations or places restrictions on where and when they can be held.
In an October 3 statement, Amnesty International called the detention of Navalny and Volkov "a blatant attempt by the Russian authorities to suppress and suffocate any dissenting voices and intimidate people trying to exercise their rights to freedom of expression and peaceful assembly.”
"Over the last few months, scores of activists across Russia have been subjected to arbitrary detention, over-the-top fines, beatings and intimidation," said Denis Krivosheev, deputy director for Europe and Central Asia at the London-based watchdog.
With reporting by RFE/RL's Russian Service, Interfax, RIA and TASS