Riot police used teargas to disperse hundreds of angry demonstrators in Tehran, chanting anti-government slogans after the value of Iranian currency plunged, sending prices in the country skyrocketing.

President Mahmoud Ahmadinejad called for calm on Tuesday but workers at the Grand Bazaar went on strike, with businessmen and workers gathering to express their fury at the fall of the rial - which has been affected by crushing sanctions imposed by the international community on the Iranian regime.

"Leave Syria alone, think of us instead" was the slogan protesters wrote on placards, according to Kaleme.com, an Iranian resistance site. Iranian leaders have supported Bashar al-Assad's regime.

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An Iranian man with a bike walks at the main bazaar, in Tehran, Iran, as two textile merchants wait for customers

Police threatened merchants who closed their shops in Tehran's main bazaar and launched crackdowns on pavement money changers on Wednesday, as part of a push to halt the plunge of Iran's currency.

But witnesses told the Guadian it is "impossible to do business in the current situation."

The head of Tehran's bazaar unions, Ahmad Karimi-Esfahani, told the BBC that shopkeepers had not opened their businesses as they were "worried about security" but he expected them to reopen on Thursday.

One witness told the Guardian : "They used teargas to disperse demonstrators in Ferdowsi Street and also blocked the streets close to the protests in order to prevent people joining them.

"Some shop windows in that area have been smashed and dustbins set on fire."

Many burnt tyres and rubbish bins. Protesters appeared to be heading for Iran's central bank, according to amateur video and police arrested many causing the disturbance.

rial

Iran's currency, the rial, has plunged to record lows

Kalame reported that the marches were "unprecedented" but were silenced by "violent repression by police."

It said store owners had protested many times against the rise in VAT but this march had been sparked by "unprecedented economic conditions, and the protesters had been unhappy and angry about the reckless remarks said in his press conference yesterday, and the government's current foreign policy."

Other slogans held aloft, according to Kalame were "We Do Not Want Nuclear Energy", "Leave Syria Now", and "Do Not Be Afraid, We Are All Together".

The BBC's Persian service and Gmail are reportedly being blocked.

The rial has lost 57% of its value in the past three months and 75% in comparison with the end of last year, with the dollar is three times stronger than early.

Ahmadinejad blamed the rial's slump on Iran's enemies abroad, Western sanctions and dissent within the country.

But media in the country, including many news outlets usually sympathetic to the regime and President Ahmadinejad have blamed the crisis on financial mismanagement.

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  • This photo, taken by an individual not employed by the Associated Press and obtained by the AP outside Iran shows, Iranians stand in a street as a garbage can is set on fire, in central Tehran, near Tehran's old main bazaar, on Wednesday, Oct. 3, 2012. Police threatened merchants who closed their shops in Tehran's main bazaar and launched crackdowns on sidewalk money changers on Wednesday as part of a push to halt the plunge of Iran's currency, which has shed more than a third its value in less than a week. (AP Photo) EDITORS NOTE AS A RESULT OF AN OFFICIAL IRANIAN GOVERNMENT BAN ON FOREIGN MEDIA COVERING SOME EVENTS IN IRAN, THE AP WAS PREVENTED FROM INDEPENDENT ACCESS TO THIS EVENT.

  • In this photo taken by an individual not employed by the Associated Press and obtained by the AP outside Iran, an Iranian fire fighter extinguishes a burned motorcycle in a street in central Tehran, near Tehran's old main bazaar, on Wednesday, Oct. 3, 2012. Police threatened merchants who closed their shops in Tehran's main bazaar and launched crackdowns on sidewalk money changers on Wednesday as part of a push to halt the plunge of Iran's currency, which has shed more than a third its value in less than a week. (AP Photo) EDITORS NOTE AS A RESULT OF AN OFFICIAL IRANIAN GOVERNMENT BAN ON FOREIGN MEDIA COVERING SOME EVENTS IN IRAN, THE AP WAS PREVENTED FROM INDEPENDENT ACCESS TO THIS EVENT.

  • In this picture taken on Saturday, July 14, 2012, Iranians make their way in the main bazaar in Tehran, Iran. Police threatened merchants who closed their shops in Tehran's main bazaar and launched crackdowns on sidewalk money changers on Wednesday, Oct. 3, 2012 as part of a push to halt the plunge of Iran's currency, which has shed more than a third its value in less than a week. (AP Photo/Vahid Salemi)

  • In this picture taken on Saturday, July 14, 2012, an Iranian man with a bike walks at the main bazaar, in Tehran, Iran, as two textile merchants wait for customers. Police threatened merchants who closed their shops in Tehran's main bazaar and launched crackdowns on sidewalk money changers on Wednesday as part of a push to halt the plunge of Iran's currency, which has shed more than a third its value in less than a week.(AP Photo/Vahid Salemi)

  • IRAN-NUCLEAR-POLITICS-AHMADINEJAD

    Iranian President Mahmoud Ahmadinejad laughs during a press conference in Tehran on October 2, 2012. Iran will not back down on its nuclear programme despite economic problems caused by Western sanctions, Ahmadinejad said. AFP PHOTO/ATTA KENARE (Photo credit should read ATTA KENARE/AFP/GettyImages)

  • Mahmoud Ahmadinejad

    Iranian President Mahmoud Ahmadinejad speaks at a press conference in Tehran, Iran, Tuesday, Oct. 2, 2012. Ahmadinejad blamed the steep drop in Iran's currency Tuesday to "psychological pressures" linked to Western sanctions over Tehran's nuclear program. The remarks were part of his attempt to deflect criticism from political rivals that his government's policies also have contributed to the nosedive of the Iranian rial, which has lost more than half its value against the U.S. dollar this year and has sharply pushed up costs for many imported goods. (AP Photo/Vahid Salemi)

  • Mahmoud Ahmadinejad

    Iranian President Mahmoud Ahmadinejad speaks at a press conference in Tehran, Iran, Tuesday, Oct. 2, 2012. Ahmadinejad blamed the steep drop in Iran's currency Tuesday to "psychological pressures" linked to Western sanctions over Tehran's nuclear program. The remarks were part of his attempt to deflect criticism from political rivals that his government's policies also have contributed to the nosedive of the Iranian rial, which has lost more than half its value against the U.S. dollar this year and has sharply pushed up costs for many imported goods. (AP Photo/Vahid Salemi)

  • Mahmoud Ahmadinejad

    Iranian President Mahmoud Ahmadinejad speaks at a press conference in Tehran, Iran, Tuesday, Oct. 2, 2012. Ahmadinejad blamed the steep drop in Iran's currency Tuesday to "psychological pressures" linked to Western sanctions over Tehran's nuclear program. The remarks were part of his attempt to deflect criticism from political rivals that his government's policies also have contributed to the nosedive of the Iranian rial, which has lost more than half its value against the U.S. dollar this year and has sharply pushed up costs for many imported goods. (AP Photo/Vahid Salemi)

  • This photo, taken by an individual not employed by the Associated Press and obtained by the AP outside Iran shows Iranian police officers blocking a street as garbage cans are set on fire, in central Tehran, near Tehran's old main bazaar, on Wednesday, Oct. 3, 2012. Police threatened merchants who closed their shops in Tehran's main bazaar and launched crackdowns on sidewalk money changers on Wednesday as part of a push to halt the plunge of Iran's currency, which has shed more than a third its value in less than a week. (AP Photo) EDITORS NOTE AS A RESULT OF AN OFFICIAL IRANIAN GOVERNMENT BAN ON FOREIGN MEDIA COVERING SOME EVENTS IN IRAN, THE AP WAS PREVENTED FROM INDEPENDENT ACCESS TO THIS EVENT.

  • In this Tuesday, Aug. 14, 2012 photo, a group of Iranian workers protest in front the Industrial Ministry building in Tehran, Iran, demanding their delayed salaries. For weeks, a manifesto complaining about Iran's sinking economy circulated in secret among factories and workshops. In the end, some 10,000 signatures were on a petition addressed to Iran's labor minister calling attention to the street-level fallout from Western sanctions: rising prices, fewer jobs. (AP Photo)

  • In this Tuesday, Aug. 14, 2012 photo, a police colonel, center, talks with a group of Iranian workers during their protest in front of the Industrial Ministry building in Tehran, Iran, demanding their delayed salaries. For weeks, a manifesto complaining about Iran's sinking economy circulated in secret among factories and workshops. In the end, some 10,000 signatures were on a petition addressed to Iran's labor minister calling attention to the street-level fallout from Western sanctions: rising prices, fewer jobs. (AP Photo)