By Aisha Labi

Iranian security forces have stepped up their response to student protests that have engulfed universities across the country this week, "ambushing" and "attacking" protesters on the campus of the University of Tehran, according to one student's e-mail account, and arresting hundreds of demonstrators.

"The jails are full of students," the student wrote in a message to The Chronicle on Wednesday. Several of his friends were among the reported 200 protesters who had been arrested in Tehran since the protests began on Monday, he wrote. More than 400 protesters reportedly have been arrested in all.

The specifics of his account and other reports that have appeared could not be fully verified, as Iran has cracked down on external news coverage of the demonstrations. But the student's account mirrored some details given by an Iranian-American scholar who has followed events from afar and those in an article by The Washington Post, one of just a handful of Western news organizations with a correspondent in Iran.

According to the Post, "thousands of pro-government militiamen stormed the grounds" of the university and assaulted students. The militiamen, members of the Basij paramilitary force, were armed with steel clubs, electric batons, pepper spray, and tear gas.

Students began demonstrating on campuses in Tehran and other major cities on Monday, in observance of National Student Day.

Thousands of demonstrators had come to the gates of Tehran's main universities on Monday, trying to join the student protesters, but were turned away by security forces. The protests on Tuesday "played out only inside the campuses," the Post reported.

Some students continued to protest on Wednesday, according to news reports, calling for the release of those who are still in jail. And campuses remained disrupted. There were unconfirmed reports, for example, that the engineering department at the University of Tehran might postpone all examinations and cancel the remainder of the term.

Hindered Communications

Local news coverage has played down the significance of the protests, and detailed information has been slow to emerge from Iran, in part because foreign reporters in the country have been barred from covering opposition demonstrations and the authorities have disrupted e-mail and cellphone access. The University of Tehran student who wrote to The Chronicle on Wednesday said he had been unable to access e-mail since Monday.

A professor at Sharif University of Technology, also in Tehran, said in a message that he was refraining from too much e-mail communication out of safety concerns.

Iran observes National Student Day on December 7 to commemorate the 1953 killing of three University of Tehran students by security forces loyal to the then-reigning shah, but for the past decade the day has become an occasion for reformist protests. This year's observance comes after the disputed June presidential election, and the authorities began clamping down last week in anticipation of widespread student actions.

With the latest show of force, the government appears to be determined to act decisively to quell the continuing dissent. "From now on, we will show no mercy toward anyone who acts against national security," a leading government prosecutor, Gholamhossein Mohseni-Ejei, was quoted as saying on Tuesday by the official IRNA news agency. "They will be confronted firmly."

Abdolkarim Soroush, a former professor at the University of Tehran and a leading figure in the Iranian-American intellectual community, has been following events there from afar, speaking with people who witnessed the clashes at the University of Tehran and watching videos of protests on other campuses. The government's response to this week's demonstrations seems unusually intense, said Mr. Soroush, who has taught at Harvard and Princeton Universities and is now a visiting scholar at the Library of Congress's John W. Kluge Center.

Even when there have been protests, National Student Day is traditionally a solemn occasion of shared commiseration and commemoration, Mr. Soroush said. "It has never been like this, with such violence and severe protests."

'Beating the Students in Earnest'

The crowd of students at the University of Tehran was very large, perhaps in the thousands, Mr. Soroush's contacts in Iran have told him. But the pro-government forces were also numerous, and well armed, and they beat back the student protesters with brutal efficiency, he said.

"They were really beating the students in earnest, very seriously, without discrimination," he said. After the worst of the clashes had subsided, the paramilitary forces were served food and drink. "It was like a piece of theater—they came, they did their job, they got their food, and went back," Mr. Soroush said.

Another striking feature that has become evident from other demonstrations is the extent to which Iran's supreme leader, Ayatollah Ali Khamenei, has been a direct focus of the protests.

Thus far, students have met the government's determination with resolve, and they apparently intend to continue their defiance. "I think the Islamic regime didn't seem to understand the magnitude of their mistakes," the University of Tehran student wrote.