The same court today gave another two opposition figures -- Popular Front leader Vintsuk Vyachorka and Labour Party chairman Alyaksandr Buchvostau -- similar jail sentences for taking part in the unsanctioned April 26 "Chornobyl Way" rally. A fourth opposition leader, Syarhey Kalyakin of the Communist Party, is still awaiting judgment.
The "Chornobyl Way" march, ostensibly to commemorate the 20th anniversary of the disaster, was prevented from entering Minsk's October Square.
As the crowd tried to reach the square, police ordered them to move about 2 kilometers away to the Academy of Sciences, where the authorities had authorized the rally to take place.
October Square was the scene of violent clashes with police after the disputed March 19 presidential election.
Viktor Ivashkevich, deputy head of the opposition Belarusian Popular Front, and one of the main organizers of the rally, says that the majority of protestors were young.
Ivashkevich tells RFE/RL that the opposition is counting on economic problems, which might bring the regime down. If Russia raises gas prices for Belarus, he says, the country's economy will collapse and young people, workers, and pensioners will take to the streets.
Speaking at the rally near the Academy of Sciences, Milinkevich said the opposition would remove Lukashenka from power in two years: "We know how to do this. There is no need to wait for five years for us, we will eliminate the regime and will oust [President Alyaksandr] Lukashenka from power. This is our goal. We will overcome!"
The march comes a month after Belarus held a presidential election on March 19. According to official results, Lukashenka gained 83 percent and Milinkevich received 6 percent. The result was criticized as flawed by independent observers, Western governments, and the opposition. Shortly after the poll, the European Union imposed a visa ban on the president and 30 top officials.
In the weeks spanning the election, Milinkevich visited a number of European countries seeking the support of Western leaders. Speaking on April 26, he said that things are rapidly changing in Belarus and the people would not be silent any longer.
"We are not rabble, we are the people! Long live Belarus! Long live Belarus! Long live Belarus!" Milinkevich said.
Milinkevich announced that another rally would be held on May 1, a national holiday in Belarus.
Click on the image to view a photo gallery of election-day events in Belarus.
THE BELARUS ELECTION: To view a complete archive of RFE/RL's coverage of the March 19 presidential election, click here.
To read and listen to RFE/RL's Belarus Service's coverage of the vote in Belarusian, click here.