The workers were demonstrating against the growing use of short-term labor contracts.
The contracts were introduced under former President Mohammad Khatami to help make Iran's heavily state-run economy more efficient.
But demonstrators today said the contracts were impoverishing the working class and depriving people of their rights.
When President Mahmud Ahmadinejad came into office, he said one of his main goals would be to improve living conditions for Iran's working classes.
RFE/RL Iran Report
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