NGOs tracking the toll from the crackdown on the biggest protests in Iran in years have said their task has been impeded by the now two-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 5,002 people had been killed, including 4,714 protesters, 42 minors, 207 members of the security forces and 39 bystanders.

However, the group added it was still investigating another 9,787 possible fatalities.

“At least 26,852 people have been arrested,” it said.

Giving their first official toll from the protests, Iranian authorities on Wednesday said 3,117 people were killed.

The statement from Iran’s foundation for martyrs and veterans sought to draw a distinction between “martyrs”, who it said were members of security forces or innocent bystanders, and what it described as “rioters” backed by the US.

Of its toll of 3,117, it said 2,427 people were “martyrs”.

HRANA said that by issuing their own toll, the authorities had “attempted to solidify the government’s official narrative regarding the killings”.

Another NGO, Norway-based Iran Human Rights (IHR), says it has documented at least 3,428 killings of protesters by the security forces and warned that the final toll risks reaching the scale of 25,000.