Celebrities and rights groups called on Iran on Sunday to free the actor Taraneh Alidoosti, one of the most prominent figures yet arrested in its three-month crackdown on protests.
Alidoosti, 38, was arrested on Saturday, official media said, after a string of social media posts supporting the protest movement including removing her headscarf and condemning the execution of protesters.
The unrest was sparked by the death in custody of Mahsa Amini, 22, whom the morality police accused of violating the Islamic republic's strict dress code for women.
Iran blames the United States and other "enemies" for trying to destabilise the country by fuelling the demonstrations.
Other Iranian actors and prominent figures including footballers have been detained in connection with the protests, but Alidoosti has considerable international renown. She performed in award-winning films by director Asghar Farhadi, including the Oscar-winning 2016 film "The Salesman".
She attended this year's Cannes Film Festival to promote the movie "Leila's Brothers" in which she starred.
"The brave actress of Iran got arrested," fellow actor Golshifteh Farahani wrote on Instagram.
Farahani now lives in exile after falling out with the authorities. Her post included a photo of her and Alidoosti, with the Persian hashtag "free Taraneh Alidoosti".
Cameron Bailey, head of the Toronto International Film Festival, tweeted that "Taraneh Alidoosti is one of Iran's most talented and acclaimed actors... I hope she's free to keep representing the strength of Iranian cinema soon."
Prominent British actor of Iranian origin Nazanin Boniadi also took to social media in support of Alidoosti, saying she had been arrested for "posting a photo of herself without compulsory hijab in solidarity with the protestors."
Authorities in Tehran on Sunday summoned another celebrity, pop singer Amir Maghare, "to provide explanations", Tasnim news agency reported. It said the 26-year-old "is currently in detention".
Iran last month arrested two other prominent actors, Hengameh Ghaziani and Katayoun Riahi, who expressed solidarity with the protest movement and removed their headscarves in public. Both have now been released on bail.
Ghaziani was among a group of cinema figures who gathered outside Evin prison in support of Alidoosti, the reformist newspaper Shargh reported on Twitter.
The group also included Mitra Hajjar, whose arrest Shargh had reported on December 3.
The New York-based Center for Human Rights in Iran said "women are being arrested and jailed in Iran for refusing to wear forced hijabs, including prominent actress Taraneh Alidoosti. The power of women's voices terrify the Islamic Republic's rulers."
During the street protests, banners of supreme leader Ayatollah Ali Khamenei have been set alight, women have openly walked down streets without headscarves, and demonstrators have at times sought to challenge the security forces.
Alidoosti's most recent social media post was on December 8, the same day Mohsen Shekari, 23, became the first person executed by authorities over the protests.
"Your silence means the support of the oppression and the oppressor", read a post on her Instagram account.
On November 9, Alidoosti posted an image of herself without a headscarf, holding a paper with the main slogan of the protests: "Woman, life, freedom".
Images have also circulated on social media of Alidoosti shopping in Tehran without a headscarf.
She had vowed not to leave Iran and said she was prepared to "pay any price to stand up for my rights."
The judiciary's Mizan Online news website said the actor was arrested "by order of the judicial authority" as she "did not provide documentation for some of her claims" about the protests.
Her Instagram account with more than eight million followers was no longer accessible on Sunday.
The Oslo-based monitor Iran Human Rights said on Saturday Iran's security forces had killed at least 469 people in the protests.
Iran's top security body, the Supreme National Security Council, on December 3 gave a toll of more than 200 people killed in the street violence, including security personnel.
Iranian authorities have arrested at least 14,000 people, according to the United Nations.