Russian police detained several hundred people, including chess champion Garry Kasparov, on Saturday as they snuffed out an attempt by opponents of President Vladimir Putin to protest near the Kremlin.
Activists had planned to gather at a city centre square about one km (half a mile) from the Kremlin to protest at what they say is Putin's trampling of democratic freedoms and demand a fair vote to choose a new president in 2008.
Teams of riot police, acting on a ruling from the city authorities banning the protest, pounced on protesters as they appeared in small groups near the square and swiftly loaded them into buses, Reuters witnesses said.
Kasparov, a leader of the Other Russia opposition coalition that organised the protest, was taken to court in central Moscow and charged with public order offences. He was fined 1,000 roubles ($39) and released after 10 hours detention.
"Today the regime showed its true colours, its true face," said 44-year-old Kasparov, a world chess champion for over a decade. "I believe this was a great victory for the opposition because people got through and the march happened," he said.
Commenting on the police breaking up the rally, he said: "This is a different level. The Russian state has shown it no longer respects the world press, public opinion or even Russian law." He said: "Now it is a country somewhere between Belarus and Zimbabwe."
Lines of riot police had earlier linked arms and forced pedestrians off the streets into Moscow's subway system.
Groups of protesters, waving Russian flags and roses and shouting "Russia without Putin", were dispersed as they tried to make their way to another square a few kilometres away. A Reuters reporter saw several being led away to police vans.
"The authorities are afraid of their own citizens and they do not want citizens to influence what is happening in the country," Mikhail Kasyanov, also an Other Russia leader, told Reuters.
"On the eve of the elections ... of course the authorities are terribly scared of this and today's excessive actions by the police (are proof of that)," said Kasyanov, a former prime minister under Putin.
The protesters have marginal influence in Russia. The vast majority of voters back Putin, who has overseen rising incomes and political stability. Kremlin loyalists say the protesters are dangerous extremists plotting a revolution.
The protest came a day after Russian multi-millionaire Boris Berezovsky said in a newspaper interview from his London base that he was fomenting revolution in Russia. The protest organisers distanced themselves from Berezovsky.
Moscow police chief spokesman Viktor Biryukov said about 170 of the "most aggressive" protesters had been detained.
"Thanks to the well-coordinated actions of the riot police and Moscow police, we were able to prevent an illegal gathering being carried out," he said.
Deputy police spokesman Yevgeny Gildeyev later said "several hundred" had been detained. He was not more specific.
Police said they had mobilised 9,000 officers around the centre of Moscow to keep order.
"The police just didn't let us get together. It was difficult to make our point," said 28-year-old Yuri Vatsky.
Four Reuters journalists -- two photographers and two camera crew -- were detained as they covered the clashes. All four were later released without charge.
Water-cannon trucks and at least a thousand police surrounded the square, in the shadow of a statue to poet Alexander Pushkin, where protesters had planned to congregate.
"For ordinary people in Russia today, it's a contest for survival," Anastasia Krampit, 39, said as she watched the protesters drift away.