Backed by tanks, the forces swept through hundreds of houses in Saqba, an impoverished town on the capital’s outskirts that was the scene of a sprawling demonstration last week against the government of President Bashar al-Assad, who inherited power from his father, Hafez, in 2000. Human rights groups put the number of arrests there at 286 and said security forces were broadly focusing on men between the ages of 18 and 50.
Activists described the arrests as part of a campaign of intimidation that represents the government’s latest attempt to stanch seven weeks of unrest. In the early days of the revolt, Mr. Assad offered some concessions, including the lifting of a draconian emergency law, though the repeal has had little impact on the ground. As protests persisted, he followed with an armed response that has killed hundreds.
The campaign of arrests appears to have escalated in the past two weeks, and American officials suggested it might backfire as the protests build on momentum gathered over successive Fridays.
“With this policy of mass arrests, the Syrian government is turning individuals who are not normally antigovernment against the government, and they’re more likely to protest even if they weren’t demonstrating before,” an Obama administration official said. “It’s angering everybody, and it’s getting worse. They’re turning people against them.”
There are no precise numbers on the arrests. Wissam Tarif, executive director of Insan, a Syrian human rights group, said that as many as 8,000 people had been reported to be in custody or missing since the pro-democracy protests erupted across the country. In most places, Mr. Tarif said, the raids appear to have been carried out by elite security forces with the military’s help.
The administration official put the number of arrests since April 22, the day of the single largest death toll in the uprising, between 2,000 and 4,000, though Mr. Tarif said he believed the higher number was more accurate.
Amnesty International said this week that detainees were beaten with sticks and cables and sometimes deprived of food. Mr. Tarif suggested that many detainees were released after a few days so that they could tell others of their mistreatment as a way of discouraging protests.
“It’s a miserable situation,” said Khalil Maatouk, a Syrian lawyer. “I’m just trying to help these people.”
The arrests in Saqba as well as in other suburbs of Damascus — targets for a government that has sought to prevent protesters from marching on the capital — came before a day that many in Syria expect to be tumultuous.
As in past weeks, protesters have called for demonstrations after noon prayers on Friday. On a Facebook page that has served as a platform of the uprising, activists described it as “the Friday of defiance.” A slogan on the site declared, “We will challenge injustice, we will challenge oppression, we will challenge fear, and we will be freed.”
The government, meanwhile, has sought to organize rallies of its supporters in Damascus and Aleppo, the country’s two largest cities. Though episodes of dissent have been reported in both places, they remain largely quiescent, and even some activists acknowledge that the lack of popular shows of anger there has hampered their cause.
Some activists said the government was seeking to bus demonstrators from regions dominated by the Alawite sect, a pillar of the government’s power.
Across the country on Thursday, there were reports of military movements.
The Syrian state media announced that the army was withdrawing from Dara’a, a poor town in southern Syria that has emerged as a symbol of the uprising. With tanks and hundreds of troops, the army entered the town on April 25, cutting electricity, water and phone lines in a siege that has prompted solidarity protests in Syria and even neighboring Jordan. The government has cast the unrest as the work of militant Islamists and said the army had dismantled their cells.
“The army started withdrawing from Dara’a this morning after they completed their mission there,” said Ad-Dunya, a private pro-government satellite channel, which later broadcast images of an armored column departing, showered with rice thrown by women and children lining the road.
Residents, though, denied there was a major pullback, saying tanks and armored carriers remained. Though some people on the town’s outskirts left their homes on Thursday, those in the center of Dara’a stayed indoors, fearful of snipers.
For days, residents have complained of shortages of food and medicine, despite attempts by neighbors to smuggle staples into Dara’a on little used agricultural roads. A United Nations humanitarian team is expected to travel to Dara’a in coming days.
“The army did not withdraw, they redeployed,” said Mohamad Hourani, reached by satellite phone. “There are still snipers on the roofs. The siege is firmer than before.”
Mr. Hourani was speaking from Ataman, a village about 10 miles from Dara’a. He is one of the few witnesses with satellite phones who can still be reached.
Even during the week, sporadic protests have continued to erupt in towns where security forces have deployed. Homs, Syria’s third largest city, and its hinterlands have proved especially restive, and one resident, Abu Haydar, said demonstrators played a cat-and-mouse game with security forces, trying to avoid them as they gathered in some neighborhoods.
“Oh, sniper, listen, listen,” crowds chanted in Homs on Wednesday, as they taunted the police. “Here is our neck and here is our head.”
Activists in Baniyas, a town on the Mediterranean coast and the scene of repeated demonstrations, said 100 tanks had deployed to its southern outskirts. Tanks and soldiers were also reportedly headed to Rastan, a town near Homs, where as many as 18 antigovernment demonstrators were killed in protests last Friday.
“They might want to raid the city, or it might just be to terrorize us, but most people are expecting an attack,” a Baniyas resident who gave his name as Rami said by telephone. “The government is still dealing with us with the mind-set of another era.”
Insan says that 607 people have been killed since the protests began March 15.
Hwaida Saad and an employee of The New York Times contributed reporting from Beirut, and Neil MacFarquhar from the United Nations.
