Police scupper anti-Kremlin demos
Police have prevented two marches by anti-government demonstrators in Moscow and St Petersburg, detaining at least 100 protesters.
Police trucks ringed two Moscow squares where protesters were to gather, and officers arrested dozens of people.
In St Petersburg, police blocked 100 protesters from marching on the city's main thoroughfare, arresting 10 people.
The protests were the latest organised by former chess champion Garry Kasparov's Other Russia movement.
Other Russia has tried to stage several protests it calls dissenters' marches.
Among those arrested on Sunday was Mr Kasparov's fellow leader, Eduard Limonov.
The Moscow authorities had warned that Sunday's demonstration, which had not been given permission, would be "firmly stopped by law enforcement officers within the framework of the law".
The latest protests follow the founding on Saturday of a new umbrella movement for Kremlin opponents, called Solidarity.
It is named after the Polish trade union that first breached the communist dominance in the former Soviet bloc.
'Impossible to reform'
Mr Kasparov said on Saturday that Solidarity's goal was "dismantling the Putin regime".
"It is impossible to reform this regime," he told more than 100 delegates at the founding congress in the Khimki area of Moscow.
Other leaders include a former deputy prime minister, Boris Nemtsov.
A pro-Kremlin youth movement, Young Russia, set off smoke bombs outside the conference hall. Some wore monkey masks and taunted delegates by tossing bananas at them.