(CNN)With cries of "Putin out" and "Russia without thieves," mass protests took place in cities across Russia on Monday -- a day that was supposed to celebrate the nation.
Russia's anti-corruption protests explained
The national day was picked by opposition leader Alexey Navalny for the latest round of rallies designed to muster support for his bid to unseat President Vladimir Putin at next year's election.
The 41-year-old activist has been an outspoken critic of what he says is a corrupt regime led by Putin and his allies -- in particular Prime Minister Dmitry Medvedev -- and is using allegations of government impropriety to muster support.
Navalny is hoping the scale of the protests will match the turnout of demonstrations in March, when thousands took to the streets across Russia.
He was arrested and jailed for disobeying a police officer during the March protests, which appeared to be a response to a long-form "investigation" that Navalny and his Anti-Corruption Foundation posted on YouTube.
The 50-minute report claimed Medvedev has assembled "a corruption empire" of luxury properties, yachts and vineyards. It has amassed almost 23 million views since it was posted on March 2.
Medvedev denies the allegations.
The Russian authorities demand that applications be filed and approved for any rallies, protests or public events. The place and the timing must be approved by the city authorities.
However -- as was the case earlier this year -- Navalny insisted they would go ahead whether they were authorized or not.
As a result, once again, numerous arrests were made Monday. Navalny himself was detained as he left his home to head to the Moscow event.
State news service Tass reported on Navalny's arrest, but ignored the protests.
Instead, it described the large numbers of people on the streets Moscow -- which it estimated at 270,000 -- as participating "in festive events" to mark Russia Day.
A common theme in March and at the latest round of rallies is the presence of rubber ducks, waved in the air by protesters.
This is a nod to an allegation that Medvedev has a custom-made duck house at one of his lavish properties.
According to a Twitter post by OVD -- an independent group monitoring arrests -- one huge duck was "detained" by police in St. Petersburg after officers took exception to it being tossed in the air.
It will be an uphill struggle thanks to his brushes with the law. Navalny has convictions for disobeying a police officer, for which he was jailed, and of embezzlement, for which he was given a 5-year suspended sentence.
Russian laws prohibit convicted people from running for office. Navalny says the charges against him are politically motivated.
The government has certainly taken notice of previous protests.
And ahead of the latest outpouring of dissatisfaction, the Prosecutor General tried to quell the Moscow protest by declaring it illegal and warning: "Law enforcement agencies will be forced to take all necessary measures to stop provocations, mass unrest or any actions leading to a violation of public security, creating conditions for threatening the life and health of citizens."
Opinion polls have suggested persistent anger with corruption. In a survey carried out in March by the Levada Center, 65% described corruption as absolutely unacceptable.
However, few Russians blame Putin: only 17% think corruption has worsened since he became President. But many say it's endemic: 45% believe Putin wouldn't succeed in fighting corruption, the highest percentage recorded in five years.