Witnesses in Iran's capital say police have clashed with protesters who were speaking out against a plunge in the nation's currency.

Police in riot gear were reported to be breaking up the Wednesday demonstrations in central Tehran.

Iranian President Mahmoud Ahmadinejad has rejected growing domestic criticism of his domestic policies as the rial slumped to record lows against the dollar this week.

Street traders said the rial traded as low as 39,000 per dollar on the black market on Tuesday before recovering slightly. Last week it traded at about 24,000 to the dollar.

The Iranian currency has plunged in value this year as the United States and European Union tightened economic sanctions aimed at pressuring Tehran to suspend its controversial uranium enrichment program.

Political opponents of the Iranian president say his economic policies also have contributed to the currency crisis. In a report published Tuesday, Iran's Fars news agency quoted Parliament Speaker Ali Larijani as saying he believes “80 percent” of the country's economic problems are linked to government mismanagement.

In a news conference Tuesday, Mr. Ahmadinejad said government policies have nothing to do with the weakening currency. Instead, he blamed it on what he called “psychological pressure” by Iran's enemies. Mr. Ahmadinejad also said his government has enough foreign currency reserves to meet the country's needs. The weakening rial has made it difficult for Iranian companies to import products from overseas.

Many Iranians also have been scrambling to convert their rials into foreign currency to preserve their savings.

Western powers have been pressing Iran to suspend uranium enrichment because they suspect such activities are part of a covert plan to develop nuclear weapons. Iran insists its nuclear program is peaceful.