MOSCOW (AFP) - Thousands of Muscovites were due to rally Sunday in commemoration of a bloody protest one year ago in which more than 400 were detained after showing their frustration with Vladimir Putin's return to the presidency.
The "Spring March of Freedom" is being held almost a year to the day since Russian authorities deployed baton-wielding interior ministry troops to disperse a crowd of tens of thousands on the eve of Putin's May 7 swearing-in ceremony.
Dozens of demonstrators and several police officers ended up in hospital in the ensuing clashes.
More than two dozen people now face years in prison on disturbance of order charges. Several have been jailed already.
"We have to come out in defence of those who have been taken hostage," said popular writer and satirist Viktor Shenderovich. "This is our obligation." But the protest movement has grown fractured since its heyday in the winter of 2011-2012 - a time when discontent was at a peak over what were seen as stacked December 2011 parliamentary elections and Putin's decision to return to the Kremlin after completing two terms in 2000-2008.
Activists can now barely agree on how they should proceed or reconcile views that range from the far left - some even openly embracing the late Soviet dictator Josef Stalin - to those who support a Western-style democracy.
Those fissures were embarrassingly laid bare when opposition leaders failed to agree on a date to mark the first anniversary of the now infamous protest.
A smaller group will be marching on Sunday because they fear that most of its supporters work during the week.
But a much larger section that includes opposition figureheads such as the corruption fighter Alexei Navalny and novelist Boris Akunin plans to hold a rally in Moscow on Monday - exactly one year after the event.
Those coming out Sunday will be gathering under a statue of Soviet revolutionary leader Vladimir Lenin in central Moscow at 4pm (8pm Singapore time) and hope to assemble some 10,000 people.
They will then march on Bolotnaya Square opposite the Kremlin - also the scene of Monday's event - for a rally starting at 10pm Singapore time.
"We will not have as many people who are known to the public," admitted event co-organiser Mikhail Anshakov.
"But we will have speakers who have been recognised in the protest movement for a long time - they simply did not advertise themselves very much." Observers say large numbers are expected to turn out for both rallies amid growing anger over a widening crackdown on dissenting voices in the country.
"We demand changes in the constitution that forbid the same person from serving more than two terms as president," said veteran opposition member and former deputy prime minister Boris Nemtsov.
Putin's thumping March 2012 presidential victory with 63.4 percent of the vote at first seemed to take all the air out of the opposition movement.
Some decided to abandon periodic demonstrations altogether in favour of a focus on municipal elections through which they could build their ranks from the bottom up.
But Putin - an ex-KGB spy who spars often with the West and supports a strictly hierarchical political system for Russia in which all major decision are made by the Kremlin - has once against shown his authoritative streak.
He has openly blamed the winter demonstrations before his election on funding from the United States.
That message has been echoed in this year's campaign against non-governmental organisations that receive funding from the West.
These groups will now be forced to declare themselves as "foreign agents" - a derogatory term that in Russian essentially means the group is run by spies.
The authorities have also opened a series of trials against opposition leaders that could land people such as the popular Navalny - by far the most dangerous figure from the Kremlin's perspective - behind bars for 10 years.
And even neutral observers were dismayed by Moscow's decision to ban the adoption of Russian children by American families that followed Washington's denial of entry to 18 Russians for alleged human rights abuses.