Iranian anti-riot police used tear gas, batons, water cannon and, according to reports, live rounds to disperse thousands of demonstrators who gathered in central Tehran yesterday in open defiance of a ban on protests declared by the supreme leader, Ayatollah Khamenei, as the defeated presidential candidate Mir Hossein Mousavi renewed his demands for the election results to be annulled and called for a nationwide strike in case of his arrest. According to an ally, Mr Mousavi declared he was ready for martyrdom. Meanwhile, official media reported that a suicide bomber blew himself up and injured eight people at the sprawling mausoleum of Iran's revered revolutionary founder, the late Ayatollah Khomeini, south of Tehran, damaging a section of the shrine. There were fierce clashes in central Tehran, with reports saying up to four people had been killed, after protesters chanted "Death to the dictator" - a slogan used in mass demonstrations against the Shah three decades ago. Witnesses said groups numbering from dozens to hundreds gathered in various parts of the city. The BBC reported that tens of thousands had taken to the streets and amateur footage posted on a number of websites showed mass rallies, though the dates and authenticity of the videos could not be verified. Ayatollah Khamenei's warnings against "illegal" protests was underlined on the streets by a large display of regime muscle. As well as anti-riot police there were military police, Revolutionary Guards and their auxiliary, much-feared plain-clothes Basij militia. "There were police, Basij guards and Sepah [army] everywhere," one witness said. "In each square [there were] more than 100 of them in different uniforms [with] different kind of guns, batons and sprays. [There were] lots of firefighting cars in the street to spray people with water. "There were lots of youths running from the police. "The streets were full of panic." The huge security presence sealed off Enghelab (Revolution) Square where a peaceful mass rally had been planned by supporters of Mir Hossein Mousavi. He is the man millions believe was the rightful winner of the June 12 election, which they insist was "stolen" from them by the president Mahmoud Ahmadinejad with the supreme leader's apparent connivance. But the election outcome has unleashed a well of anger many suspected would prove beyond the control of the losing presidential candidates - and has left Iran gripped by its worst internal conflict since the 1979 Islamic Revolution. Millions feel insulted and betrayed by a regime they believe has refused to let their votes count and rubbed salt into their wounds by hailing the huge voter turnout on June 12 as a popular endorsement of the system's legitimacy. Many longed for a Tehran spring of greater freedom at home and an end to their country's international isolation. Yesterday was a pivotal test of the regime's determination to exert its control and authority. Tear gas billowed over Enghelab square by late afternoon as helicopters clattered overhead and ambulances sirens wailed. "The robocops beat us up badly," one protester said. "Men and women were beaten up. My whole body is bruised." Witnesses said up to 60 people were seriously beaten by police, with some being dragged away by fellow protesters. Dozens were reported hospitalized. But there were also reports of protesters catching Basijis on their motorbikes and beating them. Nearby, there were also between 1,000 to 2,000 protesters in front of Tehran University, which was cordoned off by riot police. Witnesses said protesters set fire to a building in southern Tehran used by backers of Mr Ahmadinejad. Police shot into the air to disperse rival supporters in a south Tehran street, other witnesses said. There was no independent confirmation and some analysts doubted the veracity of the reports, suggesting they could be an attempt by the authorities to stir outrage among Iranians to justify a clampdown on protesters and portray them as anti-revolutionaries and terrorists. At the same time, however, any iron-fisted repression on the streets will also further damage Ayatollah Khamenei, who is already smarting from allegations that he has cost the regime legitimacy by his staunch support for Mr Ahmadinejad's "divine" electoral victory. An ally of Mr Mousavi said he had not summoned his supporters back on to the streets. The party of the other ostensibly defeated reformist candidate, Mehdi Karrubi, said plans for a rally had been scrapped because of the lack of a permit. Both men must fear bloodshed on the streets and, as prominent - if dissenting - insiders of the Islamic state, they are seemingly unwilling to blatantly challenge its authority following the supreme leader's diktat. Earlier, the interior ministry raised the distinct possibility of punishing Mr Mousavi, 67, saying he would be "held responsible for the consequences of any illegal gatherings". For his part, Mr Mousavi harshly criticised Ayatollah Khamenei's Friday speech in which he ruled out any fraud in the election. In a statement issued on his newspaper website Kalemeh, Mr Mousavi, who has denounced the election outcome as a "shameful fraud", also reiterated his demand to cancel the result of the election, calling it an undeniable right, and vowed to side always with the Iranians to defend their rights. Witnesses said Mr Mousavi appeared among the protesters in downtown Tehran and told them that if he was arrested they should call a nationwide strike. His steely defiance is a significant and remarkable challenge to the regime, which has proved it wields immense power to repress - but dealing with a campaign of mass civil disobedience may well prove much more difficult. Earlier yesterday, Iran's highest legislative body, the Guardian Council, had said it was ready to recount a random 10 per cent of the ballot boxes. It had convened an extraordinary session, inviting Mr Ahmadinejad's three purportedly defeated challengers to discuss 646 complaints against the election results. But the president's two main reformist challengers stayed away, suggesting their lack of faith in legal channels to address their grievances. The only defeated candidate to attend the Guardian Council session was Mohsen Rezaie, the hardline former head of Iran's Revolutionary Guard. Mr Mousavi and Mr Karrubi have little faith in the staunchly conservative Guardian Council, particularly following Ayatollah Khamenei's insistence on Friday that Mr Ahmadinejad was indeed the real winner. "The legal mechanisms in our country do not allow cheating. How can one cheat with a margin of 11 million votes?" the supreme leader said. The defeated candidates and their supporters reached an entirely different conclusion: it was Mr Ahmadinejad's extraordinary margin of victory over Mr Mousavi that most aroused their suspicions of electoral fraud. Gary Sick, an Iran expert at New York's Columbia University, pithily captured the essence of Ayatollah Khamenei's historic sermon. "[His] words were stark and simple. To paraphrase: the election is over, I fully support the person [Ahmadinejad] who won, it was fair, Iranians all trust their Islamic leaders, there will be no annulment, get over it and get off the streets or there will be harsh consequences, and besides it is all the work of outside agitators, especially the United States and Britain," Mr Sick wrote on his blog. Within hours of Ayatollah Khamenei's speech on Friday, thousands of Iranians had taken to their rooftops in a symbolic and peaceful gesture of defiance, chanting "God is Great!" and "Death to the Dictator!" - both rallying cries of the 1979 Islamic Revolution. The rooftop scenes have become a nightly ritual of opposition unity, and we again replayed again last night in the knowledge that comparing today's protests to those against the Shah must infuriate the regime. Before Friday there were reports of demonstrations nationwide, although protests in the provincial cities of Tabriz, Isfahan, Shiraz and Kermanshah were said already to have been crushed. Amnesty International, the human rights organisation, said on Friday it had information of up to 10 deaths in post-election violence. Iran's state media have reported seven or eight people killed. Anger at the "stolen election" was as evident in the provinces as in Tehran. Suspicions at the official vote count were deepened because supposed support across the provinces was standard for Mr Ahmadinejad, whereas in previous elections there have been substantial ethnic and provincial variations. Official results, for instance, gave Mr Ahmadinejad 57 per cent of the vote in Tabriz, the capital of Azerbaijan province from where Mr Mousavi hails. Despite sporadic violence since the June 12 election, the regime was apparently keen to avoid a major showdown on the streets with demonstrators, which would carry damaging echoes of the scenes that went with the 1979 Islamic Revolution that toppled the US-backed Shah. Three decades ago, the Shah's security forces fired directly on student demonstrators, igniting 40-day mourning protests, which created more "martyrs" each time. Ultimately the shaken and increasingly isolated Shah did not have the appetite for mass bloodshed, and went into exile. Today, the authorities must also know that its Revolutionary Guard shock troops, and to a lesser extent, its auxiliary Basij Islamic militia, are riven by the same divisions that exist within Iranian society. In the 1997 presidential elections that delivered the reformist Mohammad Khatami a landslide victory, a majority of the Revolutionary Guard's rank-and-file voted for him. Can they be depended on to confront with violence large numbers of peaceful demonstrators who may well include their own relatives and friends? "I was forced to come here," one man, dressed in a camouflage jacket and holding a baton along with group of others blocking a street leading to Enghelab street, told a witness. "I am only a civil servant and have no intention of fighting my own people." The regime's show of muscle and its intimidation of the losing presidential candidates may have won it a short-term victory in the battle for the soul of the Islamic state. But with millions of Iranians seething with anger and disenchantment - and Mr Mousavi's continued defiant and clearly peaceful stance - it may prove in the long term to be a Pyrrhic one. mtheodoulou@thenational.ae