Crackdown on Aleppo Students Stokes Fury in Syria Antigovernment anger in Syria escalated on Friday over the harsh repression of students in Aleppo, the country's largest city, where activists reported what they called the most extensive protests there yet in the 15-month-old nationwide uprising against President Bashar al-Assad. Many thousands of demonstrators, including some government loyalists, participated in the protests, according to dispatches by activists and witnesses interviewed by telephone. Sympathy protests for victims of the crackdown on the students were also reported in several other Syrian cities in what organizers called "the heroes of Aleppo University" demonstrations, and in some cases they were broken up by security forces using live ammunition. The unrest in Aleppo, Syria's commercial hub, began after a May 3 raid by security forces on the university campus that left four students dead, and it poses a new risk for Mr. Assad's government because the city has remained a core of support for his governing minority Alawite sect throughout the uprising. A change of sentiment in Aleppo could spread in Syria. The government's worry about such an outcome appeared to be on display on Thursday in Aleppo when security forces used tear gas and beat student protesters in the full view of United Nations cease-fire monitors, with an unknown number of injuries and arrests. Protesters recorded the beatings and uploaded video to the Internet, including footage shot from inside a cease-fire monitor's vehicle. The repression appeared to inflame emotions further on Friday. "The regime's brutal crackdown against students was the straw that broke Aleppo's back," a 25-year-old anti-Assad activist, who identified himself as Huzaifa, said by telephone. The government's harsh response, he said, had "pushed even the pro-Assad Aleppo people to stand with peaceful students who were demonstrating." Video uploaded online also appeared to show that many protesters consider the United Nations monitoring mission to be farcical. One protest sign in English, in the western city of al-Qusair, read: "Dear UN Observers: 15 martyrs fell since your last visit to al-Qusair last Friday. Please don't visit us again. Frustrations confronting the United Nations" monitors, who have been in Syria for more than a month and have narrowly avoided injury on at least two occasions, were on display as well. In the Syrian capital, Damascus, Maj. Gen. Robert Mood, the commander of the monitors, said at a news conference that 260 of the total of 300 monitors were now in Syria, and he asserted that their deployment had produced a calming effect. But he also said, "No volume of observers can achieve a progressive drop and a permanent end to the violence if the commitment to give dialogue a chance is not genuine from all internal and external actors." At the United Nations, the secretary general, Ban Ki-moon, sought to clarify remarks he had made on Thursday regarding responsibility for a pair of suicide bombings in Damascus on May 10 that killed at least 55 people. Mr. Ban had said that he believed the bombings had been carried out by operatives from Al Qaeda. That explanation, which went beyond what other United Nations officials have said, is consistent with the Syrian government's view, and it bolstered Mr. Assad's contention that the uprising is really the work of foreign-backed terrorists, not a popular rebellion against his family's four-decade rule. But in remarks on Friday distributed by the United Nations press office, Mr. Ban made no reference to Al Qaeda in connection with the May 10 bombings and reiterated his exhortations for all sides in the Syrian conflict to abide by the peace plan negotiated by Kofi Annan, the special representative of the United Nations and Arab League. Reporting was contributed by Neil MacFarquhar and Hwaida Saad from Beirut, Lebanon; an employee of The New York Times from Damascus, Syria; and Robert Mackey from New York.