At least 450 people have been arrested in Mazandaran, a northern province of Iran, during the last 10 days of protests, according to the province’s chief prosecutor.
Protests sparked by the death in police custody of 22-year-old Mahsa Amini have spread across the country. They have been met with internet shutdowns and violent repression.
The official death toll in the unrest is 41, while human rights groups say the true number is more than 75.
Amnesty International said at least four children had been killed by state forces since the beginning of the protests. It described a “harrowing pattern” of “deliberate and unlawful firing of live ammunition at protesters”.
Heba Morayef, Amnesty’s Middle East and north Africa director, said: “The rising death toll is an alarming indication of just how ruthless the authorities’ assault on human life has been under the darkness of the internet shutdown.”
Iranian officials said on Monday that more than 1,200 people had been arrested as the dragnet against the protests widened. Demonstrators took to the streets again on Monday night in Tehran and elsewhere, witnesses told Agence France-Presse.
Video filmed from several floors above street level, purportedly in the city of Tabriz, showed people protesting to the sound of tear gas canisters being fired by security forces, in images published by Oslo-based group Iran Human Rights.
The group said at least 76 people had been killed in the crackdown.
Amini was visiting Tehran when she was arrested by morality police who took issue with the way she had veiled her hair. While the police maintain she died of natural causes, her family say she was tortured and killed.
“During the journey to the police station she was tortured and insulted,” Amini’s cousin Erfan Mortezaei told Sky News. “She suffered a concussion from a blow to the head. There is a report from Kasra hospital [in Tehran] that says effectively by the time she reached the hospital she was already dead from a medical point of view.”
Despite efforts to stop Iranians from accessing apps such as Instagram and WhatsApp, videos of people allegedly killed during the protests have been spreading on social media.
Parents of young people killed during the protests have expressed disappointment at the response from the international community. “People expect the UN to defend us and the protesters,” said the father of 21-year-old Milan Haghigi, quoted by Amnesty International. “I too can condemn [the Iranian authorities], the whole world can condemn them, but to what end this condemnation?”
Videos showed protests on Sunday night in Tehran and cities including Yazd, Isfahan and Bushehr.
The Norway-based Kurdish rights group Hengaw said a protest was held in Amini’s home town of Saqqez despite a heavy military presence, and there were reports of a 10-year-old girl being taken to hospital after she was shot in the northern town of Bukan.
Other reports said students at three universities in Tehran were refusing to attend lessons.
Agence France-Presse contributed to this report