Thousands of riot police and Revolutionary Guard members armed with tear gas, batons and firearms were deployed Monday outside Tehran University to prevent student demonstrations backed by the opposition, AP reported.
The large security operation suggested that authorities planned to make good on their promise to deal harshly with protesters marking the day in 1953 when three students were killed in an anti-U.S. protest. The occasion has in recent years been used by students to stage pro-reform demonstrations.
There was no word immediately available on whether demonstrations have begun inside the campus, but the witnesses said police were conducting ID checks on anyone entering the campus to prevent opposition activists from joining the students.
Security forces also sought to conceal the campus from public view, covering the main gate and the fence with banners carrying quotations by Supreme Leader Ayatollah Ali Khameini and congratulatory messages marking an important Shiite occasion celebrated Sunday.
The deployment of security forces outside Tehran University led most stores and businesses in the area to shutter down. Life in the rest of the city, however, appeared to continue normally.
Journalists working for foreign media organizations are banned from covering Monday's planned protests. They were told late Saturday by the Culture Ministry that their press cards would be suspended for three days starting Monday.
On Sunday night, government opponents braved pouring rain to climb to Tehran rooftops and shout "Allahu Akbar" and "Death to the Dictator." Also Sunday, authorities choked off Internet access to deny the opposition a vital means of communication used in the past to mobilize supporters.
Government opponents were hoping for a large turnout for Monday's demonstrations to show their movement still has momentum despite a series of government crackdowns since the country's disputed presidential election in June.
Opposition leader Mir Hossein Mousavi threw his support behind the planned student demonstrations and declared that his movement was is still alive. A statement posted on his Web site said the clerical establishment cannot silence students and was losing legitimacy in the Iranian people's minds.
"A great nation would not stay silent when some confiscate its vote," said Mousavi, who claims President Mahmoud Ahmadinejad stole the June 12 election victory from him by fraud.
Khameini, the supreme leader who has final say on all state matters, accused the opposition Sunday of exposing divisions in the country and creating opportunities for Iran's enemies.
Iran's universities have been strongholds of the opposition movement that grew out of the disputed June election, and authorities have besieged campuses nationwide with a wave of arrests and student expulsions.
The pro-government Basij militia has also recruited informers on campuses to blow the whistle on any opposition troublemakers, according to students.
Despite heavy rain Sunday night, rooftop cries of "Allahu Akbar" or "God is Great" and "Death to the Dictator" were heard from many parts of Tehran on Sunday night. The protest reprised one of the main tactics of the anti-shah movement in the 1979 Islamic Revolution and was revived in the days and weeks after the disputed elections.
The rooftop chants had not been heard since the opposition's last attempt to mobilize, a Nov. 4 rally coinciding with state-sanctioned events to mark the anniversary of the 1979 U.S. Embassy takeover. That demonstration drew far fewer protesters than at the height of the summer's unrest. But it still provoked a violent response from security forces.
For weeks after the disputed June presidential election, demonstrations triggered by claims of massive fraud in the vote brought hundreds of thousands to the streets, but the relentless crackdown that followed has taken a heavy toll.
Seeking to deny the protesters a chance to reassert their voice, authorities slowed Internet connections to a crawl in the capital. For some periods on Sunday, Web access was completely shut down - a tactic that was also used before last month's demonstration.
The government has not publicly acknowledged it is behind the outages, but Iran's Internet service providers say the problem is not on their end and is not a technical glitch.
Seeking to confine journalists working for international media to their offices during the protests, Iran's Culture Ministry suspended accreditation allowing them to report from the streets from Monday to Wednesday.
The ministry also warned the few remaining pro-reform newspapers not to publish "divisive" material, the official IRNA news agency reported.
Largely swept off the streets, the opposition relies on the Web and cell phone service to organize rallies and get its message out.
The call for Monday's demonstrations was put out on dozens of Web sites run by supporters of opposition leaders Mousavi and Mahdi Karroubi, who both ran against Ahmadinejad in the June 12 election. Most of those sites have been repeatedly blocked by the government, forcing activists to set up new ones.