Hundreds of thousands of Iranian government supporters rallied in the capital Tehran, as President Mahmoud Ahmadinejad delivered a speech marking the 31st anniversary of the revolution.
The rally took place in Azadi (Freedom) Square under a heavy security presence.
Mr Ahmadinejad told the crowds that the country had produced its first stock of 20% enriched uranium, proclaiming Iran a "nuclear state".
State TV only showed the pro-government rallies, although there have been reports of opposition demonstrations in Tehran and Isfahan.
Foreign media were only allowed to cover the official ceremonies in Azadi Square. There is a ban on covering opposition protests.
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