Iran's state-run broadcaster was apparently hacked on air Saturday, with a news bulletin interrupted by a protest against the country's leader.
A mask appeared on the screen, followed by an image of Supreme Leader Ali Khamenei with flames around him.
The group called itself "Adalat Ali", or Ali's Justice.
It comes after at least three people were shot dead when protesters clashed with security forces in new unrest over the death of Mahsa Amini.
Ms Amini was detained in Tehran by morality police for allegedly not covering her hair properly. The 22-year-old Iranian Kurd died in custody on 16 September, three days after her arrest.
Her death has sparked an unprecedented wave of protest across the country.
Saturday's TV news bulletin at 21:00 (17:30 GMT) was interrupted with images which included Iran's supreme leader with a target on his head, photos of Ms Amini and three other women killed in recent protests.
One of the captions read "join us and rise up", whilst another said "our youths' blood is dripping off your paws".
The interruption lasted only a few seconds before being cut off.
Such displays of rebellion against Ayatollah Ali Khamenei are historically rare, and he wields almost complete power within Iran. But following Ms Amini's death, there has been widespread open dissent.
Also on Saturday, social media videos emerged which seemed to show female students at a university in Tehran chanting "get lost" during a visit by President Ebrahim Raisi.
Earlier in the day, two people were killed in Sanandaj, including a man shot in his car after he sounded his horn in support of protesters. A video shared online also showed a woman shot in the neck lying unconscious on the ground in Mashhad.
In Sanandaj, a police official said a man had been killed by "counter-revolutionaries", the state-run news agency IRNA reported.
On Friday, Iran's Forensic Medicine Organisation said Ms Amini had died from multiple organ failure caused by cerebral hypoxia - and not from blows to the head, as her family and protesters contend.
Rights groups say more than 150 people have been killed since the protests in the Islamic Republic began on 17 September.
Shops in several cities have shut in support of the protesters, including in Tehran's bazaar where some set fire to a police kiosk and chased the security forces away.
The protests reaching the bazaar in Tehran will ring alarm bells with Iranian leaders who have counted the merchants as among their supporters.
https://www.bbc.com/news/world-middle-east-63188795
