About 60 protesters also were detained in St. Petersburg, Interfax reported.
There was no sign of former chess champion Garry Kasparov, one Other Russia co-leader, at Triumfalnaya Ploshchad, on Tverskaya Ulitsa, where he had vowed to hold a demonstration despite being denied permission.
Kasparov and his allies in the Other Russia said they want to draw attention to Russia's economic troubles and to protest Kremlin plans to extend the presidential term from four years to six. Kremlin critics say the planned constitutional change is the latest step in a retreat from democracy and is designed to allow Prime Minister Vladimir Putin to return for another 12 years as president.
Before the planned start of the Sunday demonstration, hundreds of police ringed the Square, which was cordoned off with metal barriers, 17 army trucks and five riot police trucks.
Police seized Other Russia co-leader Eduard Limonov, along with a handful of bodyguards as they approached the square. They were bundled into police vehicles.
Police roughly grabbed protesters who tried to enter the square. Officers could be seen detaining about 25 people and dragging several of them into a waiting truck. Some were members of a pro-Kremlin youth group that staged a counter-demonstration, dropping leaflets from a concert hall rooftop.
Two protesters climbed onto the truck and were manhandled by police, who shoved them into the vehicle through a roof hatch.
About 15 people, including a Moscow Times reporter, were seized while standing outside the barrier, bundled into a truck and taken to the Zamoskvorechye police station.
The detainees, who said they were activists with opposition groups including Kasparov's United Civil Front, the newly formed Solidarity movement and the banned National Bolshevik Party, were held for about two hours, before being released after signing promises to appear in court for administrative code violations for attending the unsanctioned event.
One detainee, 32-year-old United Civil Front activist Suren Yedingarov, said riot police had hit him in the ribs, groin and a couple of times in the face -- pointing to his swollen left eye as proof.
"As riot police were dragging a man, beating him and swearing at him, I joined the crowd in shouting 'shame,'" Yedingarov said in the holding cell at the police station. "I was then rounded up by six to eight riot police and dragged into a truck."
Another detainee, 46-year-old Democratic Union activist Yevgeny Frumkin, a thin, grey-haired man in black jeans and a brown leather coat, said he was detained for distributing the organization's newspaper.
"I always distribute this newspaper at Dissenters Marches, and there has hardly been a march at which I wasn't detained," Frumkin said.
The Moscow Times reporter was released after the newspaper provided a document confirming that she had been working at the time she was detained.
Police began removing metal barriers from the square less than two hours after the planned start of the protest.
About 50 protesters -- one carrying a United Civil Front banner -- gathered near Paveletsky Station and marched about 1 kilometer along the Garden Ring, shouting slogans such as "Russia without Putin!" before they dispersed.
The leader of Other Russia's branch in St. Petersburg, Olga Kurnosova, said at least one organizer of a protest planned in that city was detained.
St. Petersburg police said 10 people were detained when they gathered at a site separate from the one approved by authorities, Itar-Tass reported.
(MT, AP)
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