CAIRO - Riot police moved onto Egypt’s main Islamic university Saturday, firing tear gas and breaking up a strike by students that threatened to disrupt midterms. One student was killed in the melee, an administration building was torched and students fled from exam rooms.

Police said they entered eastern Cairo’s Al-Azhar campus, the site of frequent clashes in recent weeks, and deployed around other Egyptian universities to prevent supporters of ousted President Mohammed Morsi from intimidating other students trying to take exams.

Pro-Morsi activists have called for an exam boycott but deny government claims that they threatened anyone.

Students at Al-Azhar, a stronghold of Morsi supporters, have been protesting for weeks against his ouster and a subsequent state crackdown, which last week saw his Muslim Brotherhood group declared a terrorist organization. The Brotherhood dismisses the label and has vowed to keep up its protests against Egyptian-military backed authorities.

The latest confrontations came after a day of street battles across Egypt between security forces and Morsi supporters in which at least five protesters were killed and more than 260 arrested.

Rallies Friday, the main Muslim prayer day of the week, were the first major show of defiance since the Muslim Brotherhood was declared a terrorist organization.

Administrators and clerics at Al-Azhar, which is Sunni Islam’s highest seat of learning, have generally taken an accommodating stance toward the military-backed interim government that supplanted Morsi’s administration.

But the ex-president, now imprisoned and facing an array of charges, has a vocal and committed base of support among the student body, and protests demanding his reinstatement have taken place almost daily.

Deputy Prime Minister and Minister of Higher Education Hossam Eissa said authorities will go after those he said were financing nonpeaceful protests on campuses, and he accused the Brotherhood of seeking to derail student exams.

“The aim of the terrorist Brotherhood group is to call off university exams,” he said, according to comments published on the state news agency MENA. “The role of the government is to restore security especially before the referendum on the constitution.”

The government is intensifying its crackdown on Brotherhood and Morsi supporters ahead of a Jan. 14-15 constitutional referendum that they see as a milestone in the transition plan. Authorities fear that Morsi supporters will seek to derail the key vote, through protests or by violent means.

University professors and security officials accused protesting students Saturday of blocking entrances to classes and harassing students as they made their way onto campus.

A statement from the Interior Ministry, in charge of the police, said protesting students stormed several buildings on campus to “terrorize students and faculty.” It said some fired shotguns into the air and smashed furniture.

The ministry statement said the violence prompted the police to move in to disperse the crowd, leading the students to set the Faculty of Commerce building on fire.

Aya Fathy, a student spokesman, disputed the officials’ claim, saying the students were protesting peacefully. She said police moved in to break up protesters outside the faculty building, firing indiscriminately at them,and killing student Khaled el-Haddad.

She accused the police of setting the building on fire to blame the students. She said the police force was chasing students on campus.

Footage from local TV stations and social-media websites showed the campus as a battleground. Flames rose from the three-story building, with rooms inside badly torched. Battles pitting police against rock-throwing students, some armed with what appeared to be homemade guns or projectile launchers, left the campus deserted, strewn with rocks and debris.

Other images showed masked protesters on roofs of university buildings lobbing rocks at security officers, and students jumping out of windows to escape the violence.

Other video showed plainclothes security officers with sticks grabbing a woman by her veil, kicking her and taking her away.

Exams were postponed at the Faculty of Commerce and other schools on campus. The university dean said the delay will be only for hours. Osama el-Abd, the dean, told Egypt’s state news agency that alternative classrooms will be provided for the students to take the delayed exams and those scheduled today. He said an investigation will be launched to find the students behind Saturday’s violence.

The Interior Ministry didn’t mention el-Haddad’s death in its statement. But a security official confirmed that el-Haddad was killed and said 14 others were injured. He blamed the students for the violence, and said 68 students, including seven women, were arrested. He said three police officers were injured. The official spoke on condition of anonymity in line with regulations.

The violence at Al-Azhar University set off protests on a university campus in the Nile Delta city of Zagzig, where students lobbed rocks at police forces.

Since the Brotherhood’s designation as a terrorist organization, officials have warned that anyone joining the group’s protests will face strict prison sentences.

The designation has coincided with security forces’ use of old tactics, some of which have the potential to spark new violence. Officials in Egypt’s south sought help from tribes and large clans, who are traditionally heavily armed, to ward off protests by pro-Morsi supporters.

The government accused the Brotherhood of orchestrating a series of attacks by Sinai militants against troops to destabilize the transition - but have provided little evidence to prove the connection. It was the main justification for labeling the group a terrorist one.

Also Saturday, a prominent international-rights group urged the interim government to rescind its terror declaration of the Brotherhood.

Human Rights Watch said the declaration appeared to have been politically motivated, and would affect the health and education services provided by the group to thousands of beneficiaries.

The group also asserted that the Brotherhood was blamed for Tuesday’s deadly bombing of a security headquarters in northern Egypt without a legitimate investigation having been conducted by Egyptian authorities.

A separate group, the militant Islamist organization Ansar Bayt al-Maqdis, or Partisans of Jerusalem, claimed responsibility for the attack in the Nile Delta city of Mansoura, which killed 16 people.

On Saturday, security officials said they defused a homemade explosive device planted on a public transportation bus in northeast Cairo. The officials said the driver discovered the device under a passenger seat. The officials spoke on condition of anonymity because they were not authorized to brief reporters.

The Brotherhood denied that it uses violence. But amid the crackdown and with hundreds killed, the group’s supporters have become increasingly defiant. In a statement late Friday, the group accused security agencies and intelligence officials of “committing terrorism” to frame their enemies.

Information for this article was contributed by Sarah El Deeb and Mariam Rizk of The Associated Press; and by Laura King of the Los Angeles Times.

Front Section, Pages 1 on 12/29/2013