Cars drive past an anti-US billboard installed on a building at Enqelab Square in Tehran. AFP
The protests started in late December, sparked by economic grievances but turned into a mass movement against the Islamic Republic, with huge street rallies on January 8 and 9 that were the biggest in recent years.
Rights groups have accused authorities of an unprecedented crackdown by shooting directly at protesters. The demonstrations have petered out for now.
NGOs tracking the toll have said their task has been impeded by an almost three-week internet shutdown, warning that confirmed figures are likely to be far lower than the actual toll.
The US-based Human Rights Activists News Agency (HRANA) said it had confirmed that 6,126 people had been killed, including 5,777 protesters, 86 minors, 214 members of the security forces and 49 bystanders.
But the group, which has an extensive network of sources inside Iran and has tracked the protests daily since they began, added it was still investigating another 17,091 possible fatalities.
At least 41,880 people have been arrested, it said.
The group condemned "the continuation of communication control policies, the ongoing wave of arrests, and growing concerns over the safety of medical centres for the injured".
Activists have accused authorities of raiding hospitals to find injured protesters and then arresting them. The health ministry has said all people should present themselves at the hospital without worry and not treat themselves at home.
"Security agencies continue to pursue an approach centred on mass arrests, intimidation, and control of the narrative," HRANA said.
It said the reports of arrests inside hospitals "have generated new human rights concerns regarding the right to access medical care".
Giving their first official toll from the protests, Iranian authorities last week said 3,117 people were killed, the majority members of the security forces and innocent bystanders who authorities claim were killed by rioters.
Last week, Iranian authorities released a video charging that the high number of casualties during recent unrest came due to a a US/Israeli-backed “terror operation” that followed initially peaceful economic protests.
*This story was edited by Ahram Online.
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