The news agency said earlier that dozens of protesters had gathered at Ploshchad Vosstaniya, with one person handing out white pieces of paper and calling for people to "quietly and peacefully walk along Nevsky Prospect."
In response to police demands to disperse, several young protesters called on those present to join hands and walk down Nevsky Prospekt toward St. Isaac's Square, where the city legislature is located.
Police formed a ring and surrounded several protesters, arresting them and loading them onto buses. Forty protesters were arrested neat Ploshchad Vosstaniya, while 20 more were arrested in places throughout the city.
In Moscow on Thursday, seven people were arrested on Red Square for holding what police said was an unsanctioned rally, RIA-Novosti reported. But Chairman of the Presidential Council on Human Rights Mikhail Fedotov said the people were detained simply because they were wearing white ribbons and balloons.
They were released shortly after their arrest.