MOSCOW Hundreds of people took to the streets of Moscow for a second successive day on Tuesday to demand an end to Vladimir Putin's 12-year rule, defying a crackdown by tens of thousands of police reinforced by crack Interior Ministry troops.
Police said they had detained about 250 people in central Moscow when they tried to stage an unapproved rally and held about 200 more in St Petersburg, where opposition forces have also been emboldened by the prime minister's worst election setback since he took power in 1999.
After permitting the biggest opposition rally in Moscow for years on Monday evening, the police were out in large numbers. The Interior ministry said about 2,000 special troops were supporting almost 50,000 police, and some moved through the city centre in armored vehicles in a show of force.
Hundreds of pro-Putin youths also tried to spoil the rally, shouting "The people! Putin" and beating drums to drown out the opposition protesters' chants of "Russia without Putin" and "We want free elections!" A few minor scuffles broke out.
Boris Nemtsov, a liberal opposition leader, told Reuters he had been detained. Two opposition figures, blogger Alexei Navalny and Ilya Yashin, were jailed for 15 days for their role in Monday's opposition protest, the biggest in Moscow for years.
"We are not going to stop our struggle," Yashin said.
The protests are a further sign of pressure on Putin to make changes after his United Russia lost ground in a parliamentary election on Sunday, even though it was criticized by Washington and European monitors and the opposition say it was slanted in the ruling party's favor.
The election outcome highlighted growing unease with the 59-year-old leader as he plans to reclaim the presidency next year and pointed to a mood shift after years of political domination by the former KGB spy who has brooked little dissent and marginalized the liberal opposition.
"We want fair elections. Look at what they have done to our country, our Russia," said a man who gave his name only as Alexei as he was pushed by riot police into a waiting bus.
The organizers used social media such as Twitter and Facebook to attract new support from people who no longer consider Putin to be invincible.
"I had to come out today because I can't stay quiet about how they just spit on us," said Mikhail Torupov, a Muscovite who said he had hardly ever protested before.
But Maxim Mishenko, 34, said he did not want Russia to follow the same violent path as Libya and Syria.
"I don't want the same thing to happen here as in Libya or Syria. There will be no Slavic spring here in Russia if I have anything to do with it," he said.
U.S. Republican Senator John McCain said Russia could now face a revolt. In a message to Putin on Twitter, he wrote: "Dear Vlad, The Arab Spring is coming to a neighborhood near you."
But many Russian political experts have dismissed suggestions that Putin could face an uprising in a country which has little tradition of major street protests, despite the 1917 Bolshevik Revolution, and where dissent has often been crushed.
Putin, meeting United Russia representatives, said he would reshuffle the government after the presidential election he is contesting next March but promised no immediate action.
It was not enough to appease opposition leaders angered by the widespread reports that the ruling party's vote count was inflated by ballot stuffing, even though it barely held on to a majority of seats in the State Duma lower house.
Putin has high popularity ratings but has upset many people by saying he wants to swap jobs with President Dmitry Medvedev after the presidential election, opening the way for him to rule until 2024. He was booed at a sports event last month.
"It's clear that on the whole the legitimacy of the authorities is on the decline," Mikhail Prokhorov, a metals tycoon who fell out with the Kremlin, wrote in his blog.
"If nothing changes, the whole (political) structure could collapse. This system will not last five years more.
Monday's rally in Moscow attracted about 5,000 people -- a large number in a country where many protests are not allowed and demonstrators are often quickly hauled away by police. Police detained about 300 people after Monday's protest.
Putin's spokesman, Dmitry Peskov, said approved rallies could continue but added: "The actions of those who hold unsanctioned demonstrations must be stopped in the appropriate way."
The political uncertainty has affected Russians stocks and the ruble. The ruble-denominated MICEX index fell by 3.8 percent, the dollar-based RTS index dropped by 4.7 percent and the ruble was 1.3 percent down against the U.S. dollar.
(Additional reporting by Gleb Bryanski and Alexei Anishchuk, Writing by Timothy Heritage, Editing by Steve Gutterman)