POLICE in Moscow have arrested top opposition figures along with demonstrators after a protest march on the eve of Vladimir Putin's inauguration as president tried to reach the Kremlin.

The march by about 20,000 people proceeded peacefully until a small group tried to break off and cross a bridge across the Moscow River, which was blocked by police.

As more people crowded toward the bridge, police sent reinforcements to the cordon and began seizing demonstrators.

Opposition leaders Sergei Udaltsov, Alexei Navalny and Boris Nemtsov were detained.

Further rallies took place elsewhere in Russia, with six people detained after demonstrators in Vladivostok carried a black coffin bearing the word "democracy" through the city.

Many Russians are angry Mr Putin, 59, is extending his 12-year domination of Russia and fear he will stifle political and economic reform in his new term.

"Putin was illegitimately elected ... we cannot stay silent and watch this disgrace," Boris Nemtsov, a liberal opposition leader, said before the Moscow march, referring to allegations of electoral fraud.

"People who are not indifferent will come to show Putin his inauguration is not a national holiday like he thinks it is, like a coronation, it is the funeral of honest politics."