Iran's judiciary chief vowed no leniency on Sunday against the wave of unrest that has rocked the country since the death of young Kurdish woman Mahsa Amini in the custody of the morality police.
The warning from Gholamhossein Mohseni Ejei came after nine nights of protests and street clashes, and it echoed earlier comments by Iran's ultra-conservative President Ebrahim Raisi.
At least 41 people have died so far, mostly protesters but including members of the Islamic republic's security forces, according to an official toll, although human rights groups say the real figure is higher.
The judiciary chief "emphasised the need for decisive action without leniency" against the core instigators of the "riots", the judiciary's Mizan Online website said.
Hundreds of demonstrators, reformist activists and journalists have been arrested amid the mostly night-time demonstrations that have spread to scores of cities since unrest first broke out after Amini's death on September 16.
Security forces have fired live rounds and bird shots, rights groups charge, while protesters have hurled rocks, torched police cars, set ablaze state buildings, and shouted "death to the dictator".
Iran's largest protests in almost three years have been led by women, triggered by anger over the Islamic republic's strictly enforced gender-based dress code.
Amini, whose Kurdish first name was Jhina, was arrested on September 13 for allegedly breaching the rules that mandate tightly-fitted hijab head coverings and which ban, among other things, ripped jeans and brightly coloured clothes.
Some Iranian women protesters have since removed and burnt their hijabs in the rallies and cut off their hair, some dancing near large bonfires to the applause of crowds that have chanted "zan, zendegi, azadi" or "woman, life, freedom".
Iranian Academy Award-winning filmmaker Asghar Farhadi was the latest to add his voice of support for Iran's "progressive and courageous women leading protests for their human rights alongside men".
"I saw outrage and hope in their faces and in the way they marched in the streets," he said in a video message on Instagram. "I deeply respect their struggle for freedom."
The world has learnt of the violence largely through shaky mobile phone footage posted on social media, even as authorities have throttled internet access.
Web monitor NetBlocks reported that Mobinnet, one of Iran's largest network operators, saw a "nation-scale disruption", with WhatsApp, Instagram and Skype having already been blocked.
This followed older bans on Facebook, Twitter, TikTok and Telegram.
Protests abroad have been held in solidarity with Iranian women in Athens, Berlin, Brussels, Istanbul, Madrid, New York and Paris, among other cities.
Iran -- which is ruled by supreme leader Ayatollah Ali Khamenei, 83, and which has been hit with tough economic sanctions over its nuclear programme -- has blamed "foreign plots" for the unrest.
The foreign ministry said Sunday it had summoned Britain's ambassador over what it described as an "invitation to riots" by Farsi-speaking media based in London, and Norway's envoy over "unconstructive comments" made by his country's parliament speaker.
Foreign ministry spokesman Hossein Amir-Abdollahian criticised "the US interventionist approach in the affairs of Iran... including its provocative actions in supporting the rioters".
Iran has also organised large rallies in defence of the hijab and conservative values.
Pro-government rallies were held Sunday, with the main event taking place in Enghelab (Revolution) Square in central Tehran, where demonstrators voiced support for mandatory hijab laws.
"Martyrs died so that this hijab will be on our head," said demonstrator Nafiseh, 28, adding that she was opposed to making the wearing of the hijab voluntary.
Another demonstrator, 21-year-old student Atyieh, called for "strong action against the people who are leading" the protests.
The main reformist group inside Iran, the Union of Islamic Iran People's Party, however, has called for the repeal of the mandatory dress code.
Human rights groups based abroad have sought to shine light on the turmoil rocking Iran, citing their own sources in the country.
Oslo-based group Iran Human Rights has put the death toll at 54, excluding security personnel.
Iranian authorities have yet to state the cause of death of Amini, who activists say died as a result of a blow to the head.
Interior Minister Ahmad Vahidi has said Amini was not beaten and that "we must wait for the final opinion of the medical examiner". (AFP)