Protests in Moscow against Putin inauguration

Baton-wielding and helmeted police have clashed with tens of thousands of protesters taking part in a demonstration against Monday's inauguration of Vladimir Putin, Russia's president-elect, arresting at least 400 in Moscow.

Those arrested on Sunday included Alexei Navalny, the anti-corruption crusader, liberal leader Boris Nemtsov and ultra-left wing activist Sergei Udaltsov.

The three men are key leaders of the nascent protest movement against Putin, who served as president and prime minister before he was re-elected in March. 

Police said they detained the protesters after they threw stones and water bottles at officers and blamed the violence on opposition leaders who attempted to stage a sit-in protest in the middle of the crowd.

Earlier, reports said at least 20,000 opposition protesters took part in the demonstration, which had been billed as a "March of Millions".

The protesters marched shouting "enough lies" while helmeted police, using batons, beat back dozens of mostly young protesters at the event across the river from the Kremlin.

The turnout appeared smaller than most of the winter's unprecedented wave of protests, some of which attracted crowds estimated at 100,000 or more.

National parliamentary elections were marred by fraud, but Putin won the vote easily and another round in March, returning to the Kremlin seat he held in 2000-2008.

Some of the demonstrators acknowledged that Putin's election win and his inauguration have been a blow to morale.

Putin will return to the presidency after an absence of four years in which he served as prime minister. The outgoing President, Dmitry Medvedev, was widely seen as an ally of Mr Putin.

He won a third term as president in controversial elections in March.

If he completes his six-year term, Putin will be the longest serving Russian leader since Joseph Stalin.

However, Putin faces many problems; the political system he created has been showing cracks, economic growth is forecast to slow, and violence in the volatile North Caucasus continues.