Syarhey Lyashkevich was arrested on March 14, five days before elections in which President Alyaksandr Lukashenka was reelected to a third term.
Opposition politicians say Lyashkevich was accused of instructing activists how to behave in the case of street demonstrations.
Election Day In Images
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.