Russian police have stormed a gathering of independent local deputies in the capital and detained dozens of people, reportedly accusing them of taking part in an event organized by an “undesirable” group.

A correspondent for RFE/RL’s Russian Service said officers arrived at the “Municipal Russia” event about 40 minutes after it began at Moscow’s Izmailovo Hotel early on March 13 and started taking people away.

The list of detainees numbers at least 100, according to one of the groups involved, and is a “who’s who” among politicians and NGOs critical of Russian President Vladimir Putin.

The event was organized by the United Democrats project, which is not among the entities on the list of “undesirable” organizations kept by prosecutors.

The detainees include senior Open Russia leaders Andrey Pivovarov and Anastasia Burakova, former Yekaterinburg Mayor Yevgeny Roizman, city deputies Ilya Yashin and Yuliya Galyamina, and opposition politician Vladimir Kara-Murza.

A number of journalists from independent media were also detained.

There were said to be around 150 attendees at the forum.

Reports from the scene suggested detainees were being taken away to a number of different police stations and Interior Ministry facilities in some of the more than 12 police minibuses parked outside the hotel.

Russia’s “undesirable organization” law was adopted in May 2015 amid a flurry of legislative, executive, and other restrictive efforts to further curb dissent in the country.

One of the effects has been to squeeze many nonprofit and nongovernmental organizations that receive funding from foreign sources and provide grounds to persecute their members.

Open Russia has been on the “undesirable” list since 2017, and Human Rights Watch (HRW) has said Open Russia and other groups have come under increasing pressure.

Its coordinator, Tatyana Usmanova, told local Dozhd TV that she didn’t know why police would have started targeting the United Democrats project too.

Fresh elections, which routinely include bans and disqualifications of opposition and independent candidates critical of the government, are due in the fall.

A bipartisan group of U.S. senators on March 12 called on Putin to halt what they called a “state-sponsored assault on media freedom” through the targeting of RFE/RL under a controversial “foreign agent” law.

A long list of other organizations are also targeted under that legislation.