The shutdown, also confirmed by Tehran-based outlets, comes as anti-government protests continue to escalate and demonstrators take to the streets in the capital and nationwide despite deadly crackdowns by security forces.
“The incident follows a series of escalating digital censorship measures targeting protests across the country and hinders the public's right to communicate at a critical moment,” Netblocks added.
Iran has cut internet access before during mass unrest in 2022, 2019 and 2009. Those moves coincided with deadly attacks on demonstrators which ultimate quashed the protest movements.
Social media platforms are routinely difficult for Iranians to access even in normal times, with official curbs sending many users to virtual private networks, or VPNs, to bypass official censorship.
The "digital blackout", as described by Netblocks, started immediately after huge crowds of people took to the streets across the country heeding a call for nationwide protests at 8 pm by Prince Reza Pahlavi.