 Vladimir Putin will be sworn in as Russia's president at a glittering ceremony on Monday, hours after clashes between police and protesters laid bare the deep divisions over his return to the Kremlin for six more years. The former KGB spy will take his oath before nearly 2,000 guests in the Kremlin's St Andrew Hall, the former throne room with sparkling chandeliers, gilded pillars and high Gothic vaults, before being blessed by the head of the Russian Orthodox Church and taking charge of the nuclear suitcase. He will also deliver a short speech, inspect the Kremlin presidential guard and host a lavish reception featuring only Russian food and drink. Although he has remained Russia's supreme leader for the past four years as prime minister, Putin will take back the formal reins of power he ceded to his ally Dmitry Medvedev in 2008 after eight years as president. He is returning with his authority weakened by months of protests that have polarized Russia and left him facing a battle to reassert himself or risk being sidelined by the powerful business and political elites whose backing is vital. In the latest protests on Sunday, police detained more than 400 people, including three opposition leaders, after tensions boiled over at a rally attended by about 20,000 people across the Moscow river from the Kremlin. Police hit protesters on the head with batons as they tried to stop demonstrators advancing towards them, carrying metal crowd barriers and throwing objects. The crowd fought back with flagpoles before the police eventually restored order. "Putin has shown his true face, how he 'loves' his people - with police force," said Dmitry Gorbunov, 35, a computer analyst who took part in the protest. A few kilometers (miles) across Moscow, several thousand people staged a rally supporting Putin, seen by his backers as the only leader capable of defending Russia's interests on the world stage and the guardian of the economy at home. While Putin's critics have tired of a political system that concentrates power in one man, many of his supporters welcome his domination of the country of more than 140 million. "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. RUSSIA HAS CHANGED The rival rallies underlined the rifts opened by Putin's return to the Kremlin and protests that were sparked by allegations of electoral fraud but fuelled by many Russians' frustration that one man continues to dominate the country. Some opposition activists plan to try to stage a protest outside the Kremlin before the inauguration ceremony. Although the protests had lost momentum before Sunday's rally, they have given birth to a civil society, two decades after the collapse of the Soviet Union, that is gradually chipping away at Putin's authority. Putin, who will be 60 in October, grew up in Soviet days and worked as a spy in communist East Germany, is under pressure to show he can adapt to the new political landscape. Few think he has changed much - if at all. Putin has eased up on the choreographtranquilizerics that burnished his image at his peak in Russia, such as riding horseback bare-chested and shooting a tiger with a tranquilizer gun. Harder to shake off will be his habit of seeking total control and learning to cope with political opponents and a middle class demanding more political freedom. He has to quell rivalries between liberals and conservatives battling for positions in the new cabinet under Medvedev, who is swapping jobs with Putin. The outcome of the struggle could help determine how far reforms go to improve the investment climate. The $1.9 trillion economy is in better shape than in most European countries but is vulnerable to any change in the price of oil, Russia's main export commodity. The budget is under pressure from Putin's lavish election spending promises. Putin has said he wants to attract more foreign investment by improving the business climate, reduce corruption and red tape, and end Russia's heavy dependence on energy exports. He has not spelled out how he will do this. Putin is likely, as in the past, to use tough anti-Western rhetoric on foreign policy to drum up support if times get tough in Russia. But he has never yielded his strong influence over foreign policy as premier, so a major policy shift is unlikely.