Moscow Prorest
Russian riot police scuffle with protesters during the "march of the million" opposition protest in central Moscow May 6, 2012. Russian riot police beat protesters with batons and hauled away dozens on Sunday after skirmishes broke out at a demonstration in Moscow against Vladimir Putin on the eve of his return to the presidency. Reuters/Denis Sinyakov

Russian riot police beat protesters about the head with batons and detained 250 Sunday after clashes broke out at a Moscow rally by thousands of people against Vladimir Putin on the eve of his return to the presidency.

Opposition leaders Alexei Navalny, Boris Nemtsov and Sergei Udaltsov were among those detained during violence that showed the depth of divisions and tensions in Russia as the former KGB spy starts his six-year third term on Monday.

Organizers told the BBC about 20,000 people took part in the opposition march - to an island close to the Kremlin - although police put the figure at about 8,000.

Police struck out with batons and hit several protesters on the head as they pushed back a crowd of thousands that advanced on them holding white metal crowd barriers and throwing objects, Reuters reporters at the rally said.

The demonstrators fought back with flagpoles but police formed a line with riot shields to prevent them moving toward a bridge leading across the Moscow River to the Kremlin.

Riot police waded into the crowd in small groups with arms locked, picking out people and hauling them away, then pushed forward in lines to hem protesters in and disperse them.

Putin has shown his true face, how he 'loves' his people - with police force, said Dmitry Gorbunov, 35, a computer analyst and one of many middle-income protesters who have joined protests against Putin in the past five months.

The violence came at the end of a day of protests in several cities against Putin, who will be sworn in at a lavish ceremony inside the Kremlin at which the head of the Russian Orthodox Church, Patriarch Kirill, will bless him.

Many of the protesters are angry that Putin is extending his 12-year domination of Russia, despite being undermined by protests, and fear he will stifle political and economic reform in his third presidential term.

They are also frustrated that the same faces will continue ruling the world's largest country and energy producer, ignoring the biggest protests since Putin rose to power in 2000.

Four years after Putin ushered his ally Dmitry Medvedev into the Kremlin and became premier in 2008 because of constitutional term limits, the two have agreed to swap jobs, with Medvedev set to take Putin's position as prime minister.

I trusted Putin as long as he ruled within the bounds of the constitution but our law limits the presidency to two consecutive terms. He and his clown Medvedev spat on that, said Andrey Asianov, a 44-year-old protester.

At least 20,000 people protested in Moscow under banners and flags, chanting Russia without Putin and Putin - thief. Police said four officers were hurt and Udaltsov, Nemtsov and Navalny had been detained for incitement to mass disorder.

Udaltsov, a leftist leader, was taken away as he tried to address the crowd from a stage and Navalny, an anti-corruption blogger, was dragged off after trying to organize a sit-in protest calling for Putin's inauguration to be scrapped.

Navalny urged protesters not to disperse until those arrested had been released.

Speaking to a radio station by phone from a police van, Navalny also told the protesters to insist that the authorities carry out the reforms they have promised.

In other protests, demonstrators carried a black coffin bearing the word democracy through the Pacific port city of Vladivostok. Several people were detained there and at protests in the Urals city of Kurgan and Kemerovo in western Siberia.

The Moscow protest was marred by the death of a photographer who Itar-Tass news said fell from a balcony as he tried to take pictures of the rally.

The clashes were the worst since police moved in to disperse hundreds of protesters at or after rallies the day after Putin's March 4 election victory, which the opposition said was achieved with the aid of electoral fraud.

But the sting has gone out of protests since Putin, 59, won the election with almost 64 percent of the vote.

The former KGB spy simply ignored the protests. He looked relaxed as he attended a religious ceremony led by Kirill that marked the transfer of a revered icon from a museum into the hands of the Church.

A few thousand Putin supporters attended a separate rally in Moscow that was intended to show he enjoys more support than the opposition, witnesses said.

Democracy is the power of the majority. Russia is everything, the rest is nothing! Alexander Dugin, a Kremlin-aligned nationalist, told the pro-Putin crowd.

Putin has dismissed allegations that widespread fraud helped him win the presidential election and secured victory for his United Russia party in a parliamentary poll in December, but the opposition says he was illegitimately elected.

Medvedev has pushed only limited political reforms through parliament following the protests, which at their height attracted tens of thousands of people in Moscow and St Petersburg but did not spread outside big cities.

The demonstrations have deprived Putin of his aura of invincibility, and opposition candidates have been trying to get a foothold on power in municipal elections, but the size of the protests on Sunday was unlikely to trouble the president-elect.

Even so, protesters said Sunday's rallies were another signal to Putin that Russia had changed as he returns to the Kremlin after four years absence, even if change was coming slowly two decades after the collapse of the Soviet Union.

Such protests were unthinkable until December, when anger over the electoral fraud allegations spilled over.

Civil society is taking shaping little by little. People will concentrate more on local problems and change things from the bottom up. It's clear we aren't going to march on the Kremlin, said Maria Golinchuk, 25, a kindergarten teacher.