At least 111 people have been detained across Russia as opposition activists, communists, and union members marked May Day with rallies, according to an independent group that monitors crackdowns on demonstrations.
In St. Petersburg, Russia's second-largest city, police broke up an opposition rally and detained 66 people after participants chanted slogans critical of President Vladimir Putin, OVD-Info said on May 1.
Some of the participants chanted slogans such as "Putin is a thief" and "This is our city," while others carried placards reading "Putin is not immortal."
Popular discontent has been building in Russia over recent years amid controversial pension reforms and falling living standards.
Supporters of opposition politician Aleksei Navalny were among some 2,000 marchers in St. Petersburg.
"Incredible," Navalny tweeted. "They dispersed a sanctioned march for no good reason."
Local lawmaker Maksim Reznik, who was among those detained, posted a picture showing police officers in riot gear dragging him along the ground. He was later released.
Several thousand members of the ruling United Russia party, the Communist Party, and other activists also turned out in the center of St. Petersburg.
Thousands of people also demonstrated in the capital, Moscow, and other cities, waving red flags.
According to OVD-Info, 16 people were detained during rallies in the Far Eastern city of Petropavlovsk-Kamchatsky, 10 in the Siberian city of Tomsk, and 18 others in Kursk, Makhachkala, and Novosibirsk.