Violent crackdown as thousands rally in downtown Tehran on Student Day

Update, 9:38 a.m.: Mir Hossein Mousavi issued a message to his supporters today. We're trying to find a copy of the whole message, but the Daily Telegraph has a brief excerpt:

"You fight people on the streets, but you are constantly losing your dignity in people's minds," Mr Mousavi, a former prime minister, said. "Even if you silence all the universities, what are you going to do with the society?"

An Iranian named Omid Habibinia is live-blogging for the France 24 network; some of his recent updates describe a large number of protesters being beaten by Basij with batons near Valiasr Square.

The Times of London says a number of students were able to reach Tehran University, where they've been staging sit-ins and mock funeral processions, and burning posters of Ayatollah Ali Khamenei.

Update, 8:29 a.m.: A group of protesters gathered in Tajrish Square in northern Tehran, according to the New York Times, where they were harassed by plainclothes police (Basij?) on motorcycles.

Tajrish seems like an odd place to gather -- it's very far north, far away from downtown and from the main protests near Tehran University. (It's also a wealthier part of the city.)

Meanwhile, here's another piece of video allegedly shot near Tehran University today. The usual caveats apply, but it's from a reliable source and the weather/clothing certainly seem to match what we've seen in other photos and video from today.

Update, 7:41 a.m.: This video appears to show protesters near Tehran University. As always, it's hard to tell whether the video was really shot today. It certainly looks like it, though, because the trees are mostly bare and the protesters are dressed for cold weather (it's a chilly, rainy day in Tehran).

Update, 6:58 a.m.: A source in Tehran says protests have broken out near Enqelab Square, the main square just west of Tehran University, where the regime's rally is being held. He says a group of protesters is moving towards the college of medicine -- on the northern end of Tehran University -- after being dispersed by police with tear gas in Engelab.

Original post: Thousands of Iranian police cracked down violently on protesters gathering in Tehran for pro-democracy protests, according to reports.

Police used tear gas and batons to disperse demonstrators in several squares in downtown Tehran, including Valiasr Square. At least a small number of protesters were able to gather in Valiasr Square, and reportedly marched through the streets chanting, "Death to Khamenei." News agencies report that protesters were also able to gather in Ferdowsi square.

Protesters also gathered at a number of universities around the city, including Amir Kabir University. Basij militiamen have stepped up their presence on university campuses in recent days.

A number of people have reportedly been arrested, including at least two women. The New York Times reported yesterday that the regime also arrested more than 20 mothers who gathered for a protest in Tehran's Leleh Park. The women all lost children during the protests that followed Iran's June election.

Details of the rallies have been scarce: The regime barred foreign journalists from leaving their offices today.

The mobile phone network in Tehran was shut down, as expected, and sources in Iran say Internet access has been greatly restricted.

The opposition movement -- which normally uses the Internet and SMS to coordinate its movements -- simply encouraged everyone to gather near Tehran University, where the regime's Student Day rally is being staged. Student Day commemorates the murder of three Iranian students by the Shah's security forces in 1953.

The Guardian reports that Iranian police are conducting ID checks at the university to prevent reformists from reaching the rally.

Sources say students are also gathering in universities elsewhere around Iran, including the cities of Shiraz and Kerman.