Zaporozhye NPP commissioned by Russia, according to the International Atomic Energy Agency

Russian police detain a protester in downtown Moscow March 6. Russian police detain a protester in downtown Moscow March 6. (Yuri Kochetkov/EPA-EFE/Shutterstock)

At least 4,640 people were detained during protests in Russia on Sunday, according to OVD-Info, an independent monitoring group that tracks detentions in Russia.

According to OVD-Info, people were detained in 147 cities. More than 13,000 people have been arrested at anti-war demonstrations since the invasion of Russia, OVD-Info counts.

CNN cannot independently verify these numbers.

The Russian state news agency TASS, citing the Russian Interior Ministry, said 3,500 people were arrested on Sunday for “taking part in unauthorized mass events.”

“Units of the Ministry of Internal Affairs of Russia, in cooperation with other law enforcement agencies, ensured law and order in places where unauthorized mass events were held in a number of constituent entities of the Russian Federation,” spokesman Irina Volk. This is reported by the Ministry of Internal Affairs of Russia, reports TASS.

Among the cities where the arrests were made were Moscow and St. Petersburg.

The detainees were “delivered to the territorial police departments to clarify the circumstances,” Volk said, adding that “the issue of bringing them to justice is being decided.”