US Secretary of State Hillary Clinton has expressed support for protesters in Iran, saying they "deserve the same rights as they saw being played out in Egypt".

Thousands of Iranian opposition supporters took to the streets of Tehran on Monday to protest against the country's leadership and show support for the popular uprisings in Egypt and Tunisia.

Dozens were reportedly arrested, leading to condemnation by the United States.

Amateur footage uploaded to YouTube purportedly shows police attempting to break up crowds with batons and tear gas.