MINSK, Belarus — Accounts of violent beatings of protesters and brutal mass detentions mounted in Belarus on Thursday as the country’s embattled president, Aleksandr G. Lukashenko, deployed brute force to cling to power.
Widespread protests against Mr. Lukashenko, an authoritarian who has ruled for 26 years, have gripped the Eastern European country ever since he claimed victory Sunday in a presidential election that his opponents and international governments widely saw as fraudulent.
The protests were initially largely peaceful, but riot police and military forces responded with stun grenades and rubber bullets, and could be seen pummeling unarmed protesters with their boots and batons. Dozens of journalists were among the thousands detained; those who were released reported fierce beatings and horrific conditions in overcrowded detention centers.
The scene outside a pretrial detention center in Minsk on Thursday was one of desperation and grief. Hundreds of people gathered, as they had for much of the week, looking for loved ones. On Wednesday, they had swarmed a departing ambulance, seeking scraps of news.
“We had 18 people in a cell designed for just four,” said Aleksandra V. Yurova, 31, who was detained after polls closed on Sunday. She described her cell as a room of about 90 square feet with a table in the middle and a toilet that did not flush. There was only one bottle of water to be refilled and used by all the inmates.
“The conditions were just horrible,” she said.
After one night in that cell, Ms. Yurova was released, most likely because she had a small child, she said. Her partner was detained as well, and she had not heard from him since. On Wednesday, she came to the jail to find out what happened to him.
“I don’t want to live here anymore,” Ms. Yurova said, describing how the experience changed her.
The arrests and violence appeared geared at scaring people off the streets. But protests against Mr. Lukashenko continued in Minsk, the capital, and across the country on Thursday. Footage circulating on social media showed workers walking off the job at the BelAZ truck factory in the city of Zhodzina, a crown jewel of Belarusian industry, chanting the protest movement’s message to Mr. Lukashenko — “Leave!”
Foreign journalists released from detention described scenes of systematic beatings and abuse. The Russian independent news website Znak.com published an account by one of its journalists, Nikita Telizhenko, who said he spent 16 hours detained with scores of others who were forced to lie face down in pools of blood, with some detainees at times lying on top of each other.
“The most brutal beatings were taking place all around: blows, screams, cries could be heard from everywhere,” Mr. Telizhenko wrote. “I had the sense that some of those detained had broken bones — hands, legs, spines — because with the tiniest bit of movement they shouted in pain.”
The beatings continued inside a van when Mr. Telizhenko and others were transferred to a different detention center. He was eventually released after the Russian Embassy interceded on his behalf.
Other correspondents also published harrowing accounts — noting that their status as foreigners and journalists likely spared them the worst abuse. Stanislav Ivashkevich, a correspondent for the Polish-based, Belarus-focused TV channel Belsat, described detention in a three-person prison cell with 12 other people.
“Over the course of two days we were given one loaf of bread for the whole cell,” Mr. Ivashkevich wrote. “At one point we were taken out and forced to run a gauntlet of rubber batons.”
The Belarusian Association of Journalists said it knows of at least 64 cases of journalists being detained since Sunday, and that at least seven have been severely beaten and injured.
One man died in custody, the Belarus authorities said on Wednesday. Michelle Bachelet, the United Nations High Commissioner for Human Rights, said more than 6,000 people were believed to have been detained.
Those detained included “bystanders, as well as minors, suggesting a trend of massive arrests in clear violation of international human rights standards,” Ms. Bachelet said in a statement. “Even more disturbing are the reports of ill-treatment during and after detention.”
There were signs that the beatings were part of a systematic effort to put down the protests. Belarus state television on Wednesday showed footage of six young people it said were protesters, their hands tied and their faces bruised and bloody.
“Are we going to do a revolution again?” an off-screen voice asks.
“Never again, ever,” one of those detained responds.
Ivan Nechepurenko reported from Minsk, Belarus. Anton Troianovski reported from Moscow.