Tens of thousands of students and opposition activists in Iran, chanting "death to the dictators", braved tear gas, baton charges, water cannon and threats of "merciless" retribution as they hijacked an official annual anti-US anniversary to protest against their own government. By some accounts, it was the biggest show of street dissent since the mass protests that followed President Mahmoud Ahmadinejad's "stolen" re-election in June, which plunged the Islamic republic into its worst political crisis in years.
There were unconfirmed reports of security forces firing live warning rounds into the air. The nationwide, student-led demonstrations were intended as a potent demonstration that the opposition remains defiant, determined and angry, despite a clampdown that has seen thousands arrested and mass show trials. "Security forces are beating demonstrators, men and women. Some of them are injured and bleeding," said a witness in a central Tehran square.
Earlier, Mr Ahmadinejad's main rival and ostensibly defeated election challenger, Mir Hossein Mousavi, declared that the opposition movement was "alive", as he warned the clerical establishment that attempts to quell protests were pointless. The authorities were "fighting with shadows in the streets", he said. "A great nation will not stay silent when some confiscate its vote." Mr Mousavi persisted: "Let's say you suppress the students and silence them [today]. What will you do with the social realities? What will you do on the following days?" On the streets, protesters chanted: "Mir Hossein, we support you."
The opposition is planning even bigger demonstrations to mark the Shia festival of Ashura at the end of the month. Well-rehearsed Revolutionary Guards, riot police and plainclothes Basij militiamen, anticipating yesterday's protests, sealed off universities to prevent protesters subverting official rallies to mark National Students Day. Security forces faced a two-pronged challenge: to prevent protesters entering university campuses to undermine official rallies and to block dissident students leaving campuses to demonstrate at other venues.
Clashes were reported in at least two of the capital's main squares as militiamen, some mounted on motorcycles, piled into crowds of protesters, battering men and women on the heads and shoulders with batons, while security forces choked them with tear gas. One witness said at least 10 protesters were arrested and whisked off to detention centres in mini-buses. Internet services and Iran's mobile phone network were crippled to deny protesters the means to communicate, organise or broadcast news of their activities.
Even so, the internet was soon brimming with grainy mobile phone camera footage of the unrest. Some showed protesters burning images of Iran's supreme leader, Ayatollah Ali Khamenei, which would have been unimaginable before his summer's anointment of Mr Ahmadinejad's re-election as a "divine blessing". State media reluctantly acknowledged that there had been clashes between "law enforcement officials" and what they called "rioters". Independent verification of many reported incidents on a day of fast-moving events was difficult because the authorities had ordered journalists working for foreign media to stay in their offices.
Saturation security measures sealed off Tehran University, a cradle of the 1979 Islamic revolution, where the main state rally was held. Police and Revolutionary Guard forces surrounded all university entrances and checked identity cards to prevent opposition activists entering to overwhelm loyalist students. Students played a major role in toppling the repressive, pro-US shah, Mohammad Reza Pahlavi, but later became a bedrock of a reformist movement pushing for a more liberal system.
"We are asking all people to come to universities so we can have one voice to protest at the coup d'état," said an online statement posted by students of Tehran's prestigious Amir Kabir University, referring to Mr Ahmadinejad's re-election, which reformists allege was fraudulent. The conservative bloc of Iran's parliament, meanwhile, demanded that Mr Mousavi and other defiant opposition leaders give up their "political obstinacy". The conservatives claimed they had "ample proof the reformists wanted to substitute the Islamic regime with a secular democracy". It was the duty of such figures as Mr Mousavi, "who have a long history in the Islamic revolution", to follow the path of Ayatollah Khamenei, "in order to make the Americans and their lackeys desperate", the conservative deputies said in a statement.
Both Mr Mousavi and Mehdi Karrubi, the other main opposition leader, have impeccable revolutionary credentials, and insist they are loyal to Iran's system. They argue that their challenge is aimed at saving the Islamic republic from dictatorship, while most of their supporters say they want gradual change, not another revolution. Mr Karrubi, in an interview with the French newspaper Le Monde, declared yesterday: "Repression is not at all the solution, neither today nor tomorrow."
Because of the ban on protests, the opposition has astutely - and subversively - used officially sanctioned demonstrations to turn out in big numbers, maintaining pressure on an infuriated and embarrassed government. Last month, the opposition put on a major show of strength on the sidelines of an official rally marking the anniversary of the 1979 seizure of the US Embassy in Tehran. Anti-government protesters also hijacked an officially sponsored anti-Israeli demonstration in September.
Yesterday's protests, on National Students Day, were in the same mould. Officially, the day is used to commemorate the anniversary of the killing of three students by security forces in an anti-US rally in 1953. A few months earlier an Anglo-American-backed coup had toppled the popular prime minister, Mohammad Mossadeq, and reinstalled the US-backed Pahlavi. Iranians have never forgotten that foreign intervention, which thwarted their democratic aspirations. One message of yesterday's protests was that those aspirations are now being denied by the regime itself. Few Iranians have been convinced by the government's attempts to scapegoat foreign powers, in particular Britain and the United States, for Iran's post-election unrest.
The "fraudulent" election aside, the authorities have embittered many students by an action on the educational system. Some university classes deemed too western - such as Marxism - have been replaced by such courses as God and Philosophy, or Islam and Social Theory, while there have been hints that professors who do not follow the official line will be purged. Student activists, their identities shielded by face masks, yesterday waved green banners, the colour of Mr Mousavi's opposition movement, as they chanted: "Don't be scared - we're all together" and "Students will die but not accept humiliation".
State television was meanwhile broadcasting a panel discussion on the loyalty of students to the system. email@example.com