At least 490 demonstrators have been killed in the mass protests in Iran over the last 15 days, the US-based Human Rights Activists News Agency (HRANA) told US television station CNN on Sunday.
Around 10,700 people have reportedly been detained, CNN reported.
The information could not initially be independently verified.
The actual death toll is likely to be higher, as Iranian authorities have almost completely blocked the population's access to the internet and phone lines.
Communication with the outside world is only possible via the Starlink satellite system, provided the necessary terminals have been brought into the country illegally.
The protests were triggered about two weeks ago by the country's crippling economic crisis, but quickly turned into political demonstrations against the apparatus of the Islamic Republic.
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