The threat of a confrontation between anti-government protesters and police in Moscow dissipated Thursday evening as the demonstrators toned down their rally in partial compliance with authorities' demands.

About 3,000 people had declared their support on Facebook for the protest in Pushkin Square calling for the release of Sergei Udaltsov, the jailed head of Russia's Left Front movement. Half that number showed up to the suppertime demonstration.

Well ahead of the event, 20 buses of riot police deployed to the square, with authorities indicating they were not inclined to allow a full-bore demonstration.

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Udaltsov is detained by police during a protest in September. He was arrested again on Dec. 4, on the eve of parliamentary elections, and has been in jail since. (Mikhail Voskresensky/Reuters)

Moscow city hall refused the demonstrators a permit on Wednesday, according to Udaltsov's wife, protest organizer Anastasia Udaltsova.

She encouraged supporters to show up anyway, but to dodge the city's protest regulations by taking to the streets without any posters or slogans, or by staging a succession of one-person pickets — neither of which requires a permit.

Those who gathered in Pushkin Square mostly followed her suggestion, as they carried no placards or banners. Instead, some people milled about the square holding up photos of Udaltsov, while others stood silently on the steps of the monument.

A few people intermittently chanted slogans calling for Udaltsov to be freed or used megaphones to make speeches.

Election fraud alleged

Udaltsov's release was one of the demands of the huge rally on Saturday in Moscow and other cities across Russia, which is witnessing its biggest protests since the 1991 collapse of the Soviet Union.

The Left Front leader was arrested the day before the country's Dec. 5 parliamentary elections on a jaywalking allegation. He has been held ever since in the same suburban Moscow detention centre used to jail Alexei Navalny, a corruption-fighting lawyer and popular blogger who spent two weeks behind bars this month for leading protests.

Udaltsov has gone on a hunger strike while in detention and been hospitalized twice.

The protests erupted in the wake of the parliamentary elections, which the opposition and European monitors say were marred by ballot stuffing and other electoral fraud favouring Prime Minister Vladimir Putin's ruling United Russia Party.