Navalny's supporters said Friday they were planning protest across 90 cities and videos and photos posted on social media showed crowds of people gathered in a number of cities across the country.

One video showed a small protest in the city of Yakutsk, where temperatures dropped to -53 degrees Celsius (- 63 Fahrenheit) on Saturday.

Moscow and St.

Be vigilant and, if possible, leave the illegal event." The Russian Ministry of Internal Affairs said about 4,000 people gathered for a protest in Moscow.

By the end of the day, more than 500 had been detained in Moscow alone, according to OVD-Info.

One of the protesters attending the Moscow rally, Kirill, said he was protesting because "you can't win a fight without fighting." Speaking to CNN at the demonstration, the 20-year old said: "I'm not proud of my country, I don't want my government to poison people and put them in prison.

Several allies of Navalny have been detained this week for inciting the protests, including his spokesperson Kira Yarmysh, Anti-Corruption Foundation investigator Georgy Alburov and opposition activist Lyubov Sobol.

The coordinator of Navalny's Moscow office, Oleg Stepanov, was detained on Saturday, according to a tweet from Navalny's Moscow team.

In a tweet posted on Saturday, the ministry said that posting information about the rallies was "in line with Washington's provocative policy of encouraging protests in countries whose governments are seen by US as undesirable."

Under Russian law, an official appeal for approval of a protest has to be made to local authorities at least 10 days before the event.