As the former Iranian president Hashemi Rafsanjani added his voice Sunday to demands for a probe of the contested June 12 presidential elections, riot police clashed with up to 3,000 protesters in north Teheran on Sunday, using tear gas and truncheons to break up Iran's first major post-election demonstration in five days. Some protesters reportedly fought back, chanting: "Where is my vote?" Others described scenes of brutality - including the alleged police beating of an elderly woman - in the clashes around the Ghoba Mosque. Other sources said the protesters, who gathered despite a heavy police presence across Teheran, also chanted "Ahmadinejad is Hitler and a holocaust is here." Revolutionary Guards and paramilitary Basijis made numerous arrests, Teheran sources said, jumping out of ambulances in some cases to apprehend protesters, and preventing onlookers from halting to watch. "The regime's agents have taken over the ambulances. Now whenever there are clashes, the hospital ambulances come to the scene. And instead of paramedics, plain-clothed agents [wearing white jackets] emerge and load up the people," one source said. According to the same source, these ambulances have also been used to secretly transport the dead from earlier clashes and bury them. "Many of the ambulances are leaving the city and coming back and then leaving the city again. It is obviousâ€¦ The police, who guard [all exits leading out of the capital], let them pass without question after the driver waves at themâ€¦The regime is doing this to cover its bloody tracks." As the Iranian authorities work to restore order, cameras and other monitoring equipment are being set up in on the main streets, especially Baharestan Square, the sources said. Plain-clothes agents and special units have also been stationed in other parts of Teheran and are stopping people with injuries for questioning, to establish whether they were involved in protest rallies. "My worker's son, who was beaten by the police a few days ago, had a bruise on his left cheek," said one source. "Today, when he was out on the streets, a plain-clothed government agent stopped him. The agent taunted him, asking him sarcastically whether he was heading to his next terrorist meeting. But the young man had the presence of mind to tell the agent that his father was angry with him and that the bruise on his face was from his father's hand." Meanwhile, trading has largely come to a halt in the Teheran bazaar over the last two days, including in the carpet-sellers' section. Most merchants there are of Turkish decent, from the Tabriz province. Tabriz closed down its local bazaar on Saturday. "I think the people in the bazaar understand that the regime is not working for our nation's interest. All of our oil money is going abroad," a Teheran source said Sunday. Supreme Leader Ali Khomeini "promised to put our country's oil money on our dinner tables, but now its going to the Arabsâ€¦ while our people are dying of starvation and this regime is talking about building hospitals in Lebanon." North Teheran, scene of Sunday's protests, is a base of support for opposition leader Mir Hossein Mousavi, who has alleged massive fraud in Iran's disputed June 12 presidential election and insists he - not President Mahmoud Ahmadinejad - is the rightful winner. Sunday's clashes broke out at a rally that had been planned to coincide with a memorial held each year for Ayatollah Mohammad Beheshti, who came to be considered a martyr in the Islamic Republic after he was killed in a 1981 anti-regime bombing. It was Iran's first significant election-related unrest since Wednesday, when a small group of rock-throwing protesters who had gathered near parliament was quickly overwhelmed by police forces using tear gas and clubs. Iran's standoff with the West over its crackdown on opposition protesters escalated Sunday after authorities detained several local employees of the British Embassy in Teheran - a move that Britain's foreign secretary called "harassment and intimidation." The European Union condemned the arrests. Iranian media said eight local embassy staff were detained for an alleged role in postelection protests, but gave no further details. British Foreign Secretary David Miliband said "about nine" employees were detained Saturday and that four had been released. EU foreign ministers meeting in Corfu, Greece, issued a statement Sunday condemning the arrests and calling for the immediate release of all those still detained. The 27-nation bloc also denounced Iran's continuing restrictions on journalists. "They make clear to the Iranian authorities that harassment or intimidation of foreign or Iranian staff working in embassies will be met with a strong and collective EU response," the statement said. Iran has accused the West of stoking unrest, singling out Britain and the US for alleged meddling and for expressing concern about the ferocity of the regime's crackdown on protesters. Last week, Iran expelled two British diplomats, and Britain responded in kind. Iran has also said it is considering downgrading diplomatic ties with Britain. On Sunday, the semiofficial Fars news agency reported that the embassy staffers were detained for what was described as a "significant role" in post-election unrest. Miliband, in Corfu for the EU meeting, said Britain lodged a protest with the Iranian authorities over the detentions. He described the step as "harassment and intimidation of a kind that is quite unacceptable. "The idea that the British Embassy is somehow behind the demonstrations and protests that have been taking place in Teheran. ... is wholly without foundation," he said. Iran's leaders have countered Western condemnation with increasingly angry rhetoric. The confrontation appears to be dashing hopes for a new dialogue, as initially envisioned by President Barack Obama when he took office. Obama wants to engage Iranian leaders in talks over the country's suspect nuclear program which the US and other western countries worry is aimed at developing nuclear weapons. Iran defends its nuclear program as civilian in nature. On Sunday, Iran's supreme leader, Ayatollah Ali Khamenei, called for national unity, appealing to both sides in the dispute, even though he has come down firmly on the side of Ahmadinejad. "I admonish both sides not to stoke the emotions of the young or pit the people against each other," he said in comments carried on state TV. "Our people are made of one fabric." But Mousavi signaled he is not dropping his political challenge. In a new statement, he insisted on a repeat of the election and rejected a partial recount being proposed by the government. However, Mousavi's challenge seemed largely aimed at maintaining some role as an opposition figure. The latest statement by Mousavi, who has been increasingly isolated, appeared Sunday on Ghalamnews, a Web site run by supporters. Meanwhile, the Al-Arabiya satellite television news channel quoted a "high-ranking" source in Qom claiming that Rafsanjani, a key supporter of Mousavi, has garnered enough support among leading Iranian clerics to remove Khamenei, but that an announcement is being delayed amid differences on who or what should replace the supreme leader. There was no independent confirmation of this report. Rafsanjani is known to have met with the Iraq-based Grand Ayatollah al-Sistani's representative in Iran, Javad Shahrestani. Some sources have raised the unlikely possibility of Al-Sistani, who has been quoted as saying that "Islamic jurisprudence holds the killing of a single human being is like the killing of all humanity," issuing a fatwa condemning the regime brutal response to post-election protests. Al-Sistani is said by some sources to have an ongoing feud with Ahmadinejad. He reportedly refused to see Ahmadinejad when the latter visited Iraq in March 2008, having never previously refused to meet an Iranian leader. Rafsanjani called on Sunday for a systematic and just probe into claims of fraud in the June 12 national elections, Reuters reported.