Iran summoned the British and Norwegian ambassadors over what it called interference and hostile media coverage of the nationwide unrest triggered by the death of a woman detained by the morality police.
Iranian Foreign Minister Hossein Amirabdollahian also criticised US support for ‘rioters’ - the label Tehran has used for many who have joined the protests which have swept the country, prompting a security crackdown and curbs on internet and phones, reports Reuters.
Demonstrations which erupted more than a week ago at the funeral of a 22-year-old Kurdish woman named Mahsa Amini, who died in detention after being arrested by police enforcing the Islamic Republic's strict restrictions on women's dress, have turned into the biggest protests in years.
Clashes continued between security forces and protesters in several northwestern regions, according to sources in the cities of Tabriz, Urmia, Rasht and Hamedan. Activists said there were also protests in districts of the capital, Tehran.
A main teachers union, in a statement posted on social media on Sunday, called for teachers and students to stage the first national strike since the unrest began, on Monday and Wednesday.
It urged teachers, trade unions, military veterans and artists to "stand with pupils, students and people seeking justice in these difficult but hopeful days".
Details of casualties have trickled out slowly, partly because of the restrictions on communication.
The sister of a 20-year-old woman identified as Hadis Najafi told a US-based activist that she died on Wednesday after being shot by security forces. Videos of Najafi had been shared on Twitter, showing her without hijab and protesting in Karaj, 30 km (20 miles) northwest of Tehran.
European Union foreign policy chief Josep Borrell said Iran should "immediately stop the violent crackdown on protests and ensure internet access". He also called for information on the number of people killed and arrested, and an investigation into "the killing of Mahsa Amini".
President Ebrahim Raisi has said Iran ensures freedom of expression and that he has ordered an investigation into Amini's death. He also said that "acts of chaos" were unacceptable and that Iran must deal decisively with the unrest. At the United Nations, he said extensive coverage of Amini's case was "double standards", pointing to deaths in US police custody.
Amirabdollahian said the United States was supporting 'rioters' and seeking to destabilise Iran, a stance he said contradicted American calls for stability in the region and for a nuclear deal with Tehran.
Iran's Foreign Ministry summoned Britain's ambassador in response to the "hostile character" of London-based Persian language media. Britain's foreign ministry said it championed media freedom and condemned Iran's "crackdown on protesters, journalists and internet freedom".
Norway's envoy was also summoned to explain the "interventionist stance" of its parliament speaker Masud Gharahkhani, who has expressed support for the protesters.
Gharahkhani, who was born in Tehran, continued to speak out on Sunday, writing on Twitter: "If my parents had not made the choice to flee in 1987, I would have been one of those fighting in the streets with my life on the line."
Amini's death has reignited anger in Iran over issues including restrictions on personal freedoms, the strict dress codes for women and an economy reeling from sanctions.
Women have played a prominent role in the protests, waving and burning their veils. Some have publicly cut their hair as furious crowds called for the downfall of Supreme Leader Ayatollah Ali Khamenei.
The protests are the largest to sweep the country since demonstrations over fuel prices in 2019, when Reuters reported 1,500 people were killed in a crackdown on protesters - the bloodiest bout of internal unrest in the Islamic Republic's history.
Iranian Oscar-winning director Asghar Farhadi called on activists and artists around the world to support the protesters, who he said were "looking for simple and yet fundamental rights that the state has denied them for years".
"I deeply respect their struggle for freedom and the right to choose their own destiny despite all the brutality they are subjected to," Farhadi said in a post on Instagram.
Iran's state television said 41 people have been killed since the protests broke out following Amini's death on Sept 16. The semi-official Mehr news agency said on Sunday eight members of the Basij, a militia under the umbrella of the Revolutionary Guards, were among the dead.
State media said 12 bank branches were destroyed in the unrest in recent days, and 219 ATMs have been damaged.
The Iranian human rights group Hengaw posted a video on Twitter purportedly showing protests late on Sunday in Sanandaj, the capital of Kurdistan province, with chants of "Death to Khamenei".
Activist Twitter account 1500tasvir posted videos it said showed protests on Sunday in western and eastern districts of Tehran. In one a protester could be heard saying: "They (security forces) won't get the better of us. People, I beg you to join us". Reuters could not verify the footage.
Iranian television showed thousands of people rallying in Tehran on Sunday in support of authorities and chanting slogans against the United States and opposition groups they accused of insulting the Koran.
"Sedition is the cause of riots and is directed by America," they chanted.