Western governments and human rights groups are criticizing Belarusian authorities for the biggest crackdown in years against peaceful protesters.
The crackdown over the weekend came at demonstrations across the country against a government-backed tax on the unemployed.
Maja Kocijancic, a spokeswoman for the European Union’s foreign policy chief, said on March 13 that "the detention and sentencing of peaceful protesters, including leaders of opposition movements, is in contradiction with Belarus' declared policy of democratization."
The EU called for the immediate release of all the detained protesters.
Meanwhile, the rights group Amnesty International lamented that civil society leaders and independent journalists were among at least 48 people detained and charged with attending "unauthorized" demonstrations across the country from March 10-12.
WATCH: Belarusian Protests Against Tax On Jobless Continue In Babruysk and Vorsha
John Dalhuisen, Amnesty’s director for Europe and Central Asia, said: "With basic freedoms strangled in Belarus, it has been years since we saw protests of this scale, which appear to have taken the Belarusian authorities by surprise."
Dalhuisen said: "After initially allowing protests against the deeply controversial unemployment tax to proceed, now the authorities have returned to their habitual knee-jerk reaction of arresting peaceful demonstrators."
He said the "escalation is disturbing" and that the "arbitrary detention of dissenting voices must end immediately."
Amnesty noted that authorities cracked down on rallies in the cities of Babruysk, Kobryn, Brest, Luninets, and Maladzyechna as well as the eastern city of Vorsha where dozens were detained on March 12.
WATCH: Hundreds Protest In Pinsk Against Tax On Jobless (March 11)
It also criticized Belarusian court rulings that sentenced at least three activists to 15 days in jail and issued fines against others, including journalists who were arrested while reporting on the demonstrations.
In Vorsha, prominent opposition figure Pavel Sevyarynets was among those detained on March 12, along with RFE/RL Belarus Service reporter Halina Abakunchyk.
On March 13, a court in Vorsha fined Abakunchyk about $300.
Abakunchyk pleaded not guilty and insisted she was merely reporting on the protest march against taxing the unemployed.
Abakunchyk said police forcibly detained her without letting her show her press card, holding her several hours at a police station even after she told them she was working as a journalist.
Belarusian President Alyaksandr Lukashenka has said the unemployment tax is a necessary to fight what he called "social parasitism."
Protesters want the tax law scrapped and have continued demonstrations despite a March 9 order from Lukashenka that suspended implementation of the tax until 2018.
The roughly $200 tax is aimed at those who work less than six months a year and fail to register in the country’s labor bureaus.
Belarus has seen opposition protests in the past, mainly after elections that the West has deemed neither fair nor free.
But those protests have been limited to the capital, Minsk, and larger cities.
Political observers say the fact that the antitax protests are occurring in more provincial towns and cities is indicative of larger social unrest and unhappiness with Lukashenka's government.
With reporting by RFE/RL's Belarus Service and correspondent Rikard Jozwiak in Brussels