(Reuters) Riot police clashed with demonstrators and arrested money changers in Tehran on Wednesday in disturbances over the collapse of the Iranian currency, which has lost 40 percent of its value against the dollar in a week, witnesses said.

Police fired tear gas to disperse the demonstrators, angered by the plunge in the value of the rial. Protesters denounced President Mahmoud Ahmadinejad as a “traitor” whose policies had fuelled the crisis.

In a clampdown on the unofficial foreign currency market, a number of traders selling dollars were arrested after authorities ordered security forces to take action against those it sees as speculators.

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