Riot police had earlier rounded up scores of people as about 1,000 turned out for the rally in response to opposition calls on the Internet.
RFE/RL correspondent Aleh Hruzdzilovich was among those arrested, but he was subsequentlz.
He claims he was detained despite identifying himself as a journalist and that the police were acting "very brutally," as if trying to intimidate the protesters.
"I am still in the police van. Riot cops continue to bring other detained protesters into the van, brutally hitting some on their arms and legs, throwing them on the floor, cursing as they do so," Hruzdzilovich told us by mobile phone at the time.
"No one paid any attention to the fact that I'm a journalist. I was one of the first to be detained," Hruzdzilovich continued. "The commanding officer himself tore away my camera, broke my microphone, and then ordered other cops to take me in. When I resisted, four cops took me by my arms and legs and dragged me away into the van. I kept screaming, 'I'm a journalist! Help!' But that had no affect on them. I'm OK, but I spent a lot of time lying on the floor of this van, under the heels of the cops. They were very brutal."
Meanwhile, Swedish Foreign Minister Carl Bildt said the Belarusian ambassador to Stockholm would be summoned to the Foreign Ministry after a Swedish diplomat was briefly manhandled by police during the Minsk rally.
Protest calls on social-networking sites have multiplied in recent weeks as a severe currency crisis has brought economic hardship.
It was the fourth consecutive Wednesday that protests were organized via the Internet.
Police sealed off entry to Minsk's October Square near the main presidential headquarters, as they did a week ago.
When up to 1,000 people gathered on the main thoroughfare, Independence Prospect, squads of special forces moved in and hustled people into police buses.
Responding to an opposition Internet call, dozens of cars had joined the protest, driving slowly down the main thoroughfare and sounding their car horns.
There were similar protests in more than 30 other cities.
with agency reports