Thousands of Russians have marched through Moscow to protest against President Vladimir Putin.

Protesters streamed down a leafy central boulevard in the first major rally since Mr Putin was sworn in on 7 May.

They said they would not be deterred by police raids on opposition leaders' homes and a new law stiffening fines for public order offences.

Protesters waved flags and shouted "Russia without Putin".

Leftist leader Sergei Udaltsov ignored his summons for questioning about violence at a rally on the eve of Mr Putin's inauguration.

Instead, he led a group of marchers carrying red flags and chanting "Putin to jail!" and "All power to the people!"

Opposition lawmaker Ilya Ponomaryov said about 60,000 to 70,000 people had turned out, much higher than the police estimate of 18,000.

Riot police manned metal barriers along parts of the route, but the police presence was lighter compared with some earlier protests.

After tolerating the biggest protests of his 12-year rule while seeking election, Mr Putin has signalled a harsher approach to dissent since the start of his new term as president.

In power since 2000, Mr Putin easily won a six-year term on 4 March after four years serving as prime minister.

His mantra of ensuring stability finds deep support among the elderly and many outside the cities, as have his strong measures against the protesters, accused by some of his backers of being spoilt urbanites financed by foreign powers.

But opposition leaders say Vladimir Putin's heavy-handed tactics show that the former KGB spy is deeply worried by the protests that have undermined his once iron-clad authority.

Last week, he signed a law increasing fines, in some cases more than 100-fold, for violations of public order at demonstrations, despite warnings from his human rights council that it was an unconstitutional infringement on free assembly.

Police and investigators raided the apartments of Udaltsov, anti-corruption blogger Alexei Navalny and socialite Ksenia Sobchak yesterday, seizing computer drives and discs, photographs and other belongings as armed guards stood outside.