BBC:

Protest leader Alexei Navalny told the crowd to loud applause that Russians would no longer tolerate corruption.
"I see enough people here to take the Kremlin and [Government House] right now but we are peaceful people and won't do that just yet," he said.
A sea of demonstrators stretched along Sakharov Avenue, a few miles from the Kremlin, in sub-zero temperatures.
Rallies are taking place across Russia, with the first big protest in the far eastern city of Vladivostok.
In the capital, Moscow, organisers expect some 50,000 people to gather for speeches by opposition figures.
President Dmitry Medvedev announced political reforms this week, but many demonstrators say it is not enough.
Watch from MSNBC: