MOSCOW — Police in Moscow used megaphones to order anticorruption protesters to disperse as several hundred people began marching down Tverskaya Street, a central thoroughfare.
There was a heavy police presence throughout the area, and RFE/RL correspondents saw at least five people being detained.
Russian media reported that at least 50 people had been detained at an unsanctioned demonstration in the northern city of St. Petersburg.
The nationwide protest, held to coincide with the Russia Day national holiday, was organized by anticorruption activist and opposition politician Aleksei Navalny.
Navalny himself was detained by police outside his Moscow apartment building shortly before the scheduled start of the demonstration.
Navalny’s wife, Yulia Navalnaya, said on Twitter that Navalny was urging supporters to go ahead with the June 12 demonstration in central Moscow as planned.
Sources at Navalny’s Anticorruption Foundation reported that electricity and Internet access at their offices had been cut off.
Leonid Volkov, a key Navalny associate, said on a live broadcast on the opposition leader’s YouTube channel that power to their studio had been shut off. The livestream then cut out.
The Moscow demonstration began at 1100 GMT. Similar demonstrations were being held or planned in more than 200 Russian cities.
The Moscow demonstration had been planned to be held at a city-approved location outside the center. But on June 11 Navalny urged supporters to march instead on the downtown thoroughfare of Tverskaya Street, near the Kremlin.
Navalny said authorities had pressured suppliers not to provide audio, video, or other equipment for the demonstration.
Moscow authorities have said that citizens will be allowed to “stroll” on Tverskaya, which has been turned into a pedestrian zone for the Russia Day national holiday, but that anyone bearing political placards or shouting slogans would be subject to arrest.
Some of the demonstrators were seen holding toy rubber ducks, a reference to an allegation in one of Navalny’s videos that Prime Minister Dmitry Medvedev controls a lavish vacation house with a pond and duck house.
Navalny is hoping to build on momentum gained by a national anticorruption protest in March, which drew unexpectedly large crowds and ended with more than 1,000 people detained in Moscow alone. Navalny was detained in the run-up to that demonstration as well and served 15 days of administrative detention.
In Russia’s Far East, which is up to seven hours ahead of Moscow time, police detained several people participating in the anticorruption protests. At least four people were detained in Blagoveshchensk, including the organizer of the unauthorized protest there.
Local media reports said riot police scuffled with demonstrators and detained an unspecified number of people as a few hundred people protested in Vladivostok, which is seven hours ahead of Moscow.
Video footage showed helmeted officers with batons dragging two men or boys from a crowd of people while protesters shouted “Shame! Shame!”
“I’m here because of the corruption that is reaching huge proportions in Russia,” said Aleksei Borisenko, a protester in Vladivostok who said he narrowly escaped police trying to detain him. “It’s a dead end for the country’s development.”
“We have been silent, but we won’t be anymore. We will make the authorities answer!” a woman at the Vladivostok protest shouted.
Sizable crowds turned out in the Siberian city of Novosibirsk and in Barnaul, capital of the Altai Krai region bordering Kazakhstan, and protests were held in other cities — from Kazan in Tatarstan on the Volga River to the Pacific coast.
An unauthorized protest was also planned for St. Petersburg. Andrei Pivovarov, an organizer in the northern capital, posted on Facebook on June 12 that police had come to his residence and accused him of “organizing mass disorder.” After he refused to open his door, police took up positions outside, Pivovarov said.
In Moscow, Tverskaya has been turned into a pedestrian zone and the authorities have planned a celebration focusing on Russia’s military glory. Photographs on social media showed the street blocked with sandbags, antitank emplacements, and vintage military equipment.
Navalny announced the location change less than 24 hours before the protest, accusing the authorities of pressuring providers of audio, video, and stage equipment not to work with demonstration organizers.
On June 12, an anonymous pro-Kremlin Twitter account posted a video purporting to show an empty stage and sound equipment at the originally approved protest site.
In his June 11 video, Navalny called on supporters to march peacefully and not to allow themselves to be caught up in provocations.
After Navalny announced the switch, the Moscow prosecutor’s office warned that “any attempts to hold an unauthorized event on Tverskaya Street” would be illegal and “law enforcement organs will be forced to take all necessary measures” to maintain order.
In a separate statement issued hours before the planned march, Moscow police warned that “any provocative actions by protesters will be considered a threat to public order and immediately halted.”
Kremlin spokesman Dmitry Peskov said the issue was a matter for city authorities, adding that it was “important to avoid any provocations or illegal actions.”
Vladimir Chernikov, head of the city’s regional security and anticorruption department, told Ekho Moskvy radio that citizens would be allowed to stroll on Tverskaya but would not be allowed to carry signs or shout slogans.
“If someone appears with a political sign or shouting slogans, then the chances are 100 percent he will be a potential client of the police,” Chernikov said. “If a citizen is strolling peacefully and is demonstrating a spirit of solidarity with the majority of people who come out to mark Russia Day, everything will be calm and fine.”
The demonstrations were being held to protest what Navalny says is a system of corruption and cronyism that President Vladimir Putin presides over.
Navalny, 41, is trying to get on the ballot for the presidential election next March in which Putin — who has held power as president or prime minister since 1999 — is widely expected to seek and secure a fourth term as president.
Navalny has been convicted three times in financial-crimes trials that he calls Kremlin-orchestrated retribution for his activism, though he has been handed suspended sentences rather than actual prison time.
Russian authorities have suggested that he could be barred from the presidential ballot due to his criminal record. But his backers say the rules are unclear, and Russian officials have not stated clearly whether he will be allowed to run.
A day before the planned June 12 protests, a video produced by Navalny and his supporters accusing Prime Minister Dmitry Medvedev of corruption was published on two government websites.
The video, which played a central role in galvanizing protesters for the March 26 demonstrations, was published briefly on the websites of the regional prosecutor’s office in the central city of Yaroslavl and the St. Petersburg regional administration.
Yaroslavl prosecutors said they suspected their website was hacked.