Riot police detained dozens of anti-Kremlin protesters, including leading opposition figure Boris Nemtsov, in central Moscow today, defying a plea by rights group Amnesty International to let the rally go ahead.
At least 100 people gathered in protest against what they say is a long-running Kremlin campaign to dismantle the constitutional right to peaceful protest, one of the few avenues open to Russia's weak and fragmented opposition.
At a similar rally in December, police detained 82-year-old Soviet-era activist Lyudmila Alexeyeva, prompting a rebuke from the administration of US president Barack Obama.
Moscow authorities told the organisers that another event, "Winter Fun", was taking place in the centre of Moscow.
Opposition groups say the authorities routinely organise alternative events as an excuse to deny them access to central squares.
Mr Nemtsov, a former deputy prime minister, is leader of the opposition group Solidarity and one of the toughest critics of the Kremlin and Prime Minister Vladimir Putin.
Reuters