Thousands of Russians have taken to the streets of Moscow to mark one year since a major opposition protest ended in mass arrests.
Participants in Monday's rally, which went peacefully amid heavy police cordons, urged the authorities to free more than two dozen people facing criminal charges over their involvement in the protest a year ago.
Protest leader Alexei Navalny told the crowds he would keep on fighting the Kremlin in defiance of mounting criminal probes.
"We will not give up and we will not go away," he said. "[President Vladimir] Putin is a thief ... We will throw him out of the Kremlin."
Al Jazeera's David Chater, reporting from Moscow, estimated the crowd at the rally at 20,000. Only 30,000 people were allowed by the government to protest.
"It looks like a very powerful protest and it looks like it's going to be full as much as the mayor of Moscow allows," Chater said.
"It's not the case yet that Putin has completely extinguished the spark of this protest."
The opposition hopes Monday's rally will breathe new life into the protest movement following what observers say is the toughest crackdown on dissenters of Putin's 13 years in power.
The latest demonstration remembers the protests on the eve of Putin's inauguration for a third presidential term that resulted in more than 400 arrests after scuffles with riot police.
|Protest leader Alexei Navalny brought his wife
Yulia onto the stage of Monday's rally [AFP]
One activist has been jailed for four and a half years for purportedly using violence in the 2012 rally, held in the same square as Monday's protest, just across the Moscow river from the Kremlin. Another has been sentenced for two-and-a-half years.
Pro-opposition writer Boris Akunin, one of Russia's most popular novelists, said the new rally at Bolotnaya Square was the "last chance" for Russians to show the Kremlin they did not agree with its policies.
"If few people come to Bolotnaya on May 6, then the regime will see it as carte blanche from society: 'Put in prison whoever you want, we are not against it'," he wrote in his blog ahead of the rally.
Prosecutors warned the opposition against any provocations including any attempts to hold a march through the city in addition to the rally, while police said it would deploy 5,000 personnel to oversee the event.
Putin last year reasserted his authority through tough legislation which requires NGOs receiving foreign aid to register as "foreign agents", expands the definition of treason and introduces steep fines for misdemeanours at rallies.
Also on Monday, the justice ministry said it was putting on hold the registration of several political parties including the liberal Popular Alliance.
Hours before the protest began, a worker died after he was struck by acoustic equipment as he was helping to erect the stage for the event.
In Russia's second city Saint Petersburg police said about 750 people gathered in the city centre, while organisers put the turnout at over 1,500.
The last major opposition rally was held in Moscow in January when about 20,000 people took to the streets to protest a Kremlin decision to ban adoptions by Americans in retaliation to US legislation targeting Russian officials.