Iranian authorities on Wednesday released on bail star actor Taraneh Alidoosti after holding her for almost three weeks over her support for the protest movement, her lawyer said.

Alidoosti is one of Iranian cinema's most acclaimed stars, winning international renown for performances in award-winning films by director Asghar Farhadi, including the Oscar-winning 2016 movie "The Salesman".

Her detention had prompted an outcry in the film industry and amplified concern about the authorities' crackdown on more than three months of protests that has seen thousands arrested.

"My client was released on bail today (Wednesday)," lawyer Zahra Minooee told the ISNA news agency.

Images published by Iranian media, including the Shargh newspaper, showed her walking free from Tehran's Evin prison clutching flowers and notably not wearing the Islamic headscarf, in apparent defiance of Iran's strict dress laws.

Leading figures from the Iranian film industry still inside the country turned out to welcome her, including directors Mani Haghighi and Saeed Roustayi, the images showed.

Other pictures of her being driven away in a car showed her sticking out her tongue and flashing a 'V' for victory sign.

"Iranian actress Taraneh Alidoosti released after three weeks in detention: what joy and relief!" tweeted the Cannes Film Festival. "Let's stay involved!" it added.

- 'A warning' -
 

Iran has been gripped by protests since the September 16 death in custody of Mahsa Amini, an Iranian Kurd who was arrested for allegedly violating the country's strict dress code.

Alidoosti, 38, was arrested on December 17 after making a string of social media posts supporting the protest movement -- including removing her headscarf and condemning the execution of protesters.

Over 600 artists worldwide, including actors Kate Winslet and Mark Rylance and director Pedro Almodovar, had signed an open letter calling for her release.

Her arrest "was a warning to public figures in Iran as part of the Iranian regime's brutal crackdown on the nationwide Woman, Life, Freedom protests," said the petition, published on the Instagram page of Hollywood actor Mark Ruffalo.

Alidoosti had attended this year's Cannes Film Festival to promote the acclaimed movie "Leila's Brothers" in which she starred and which was directed by Roustayi.

She appeared in two of Farhadi's earliest films before he won international renown, "Beautiful City" in 2004 and "Fireworks Wednesday" in 2006.

Alidoosti then appeared in the 2009 film "About Elly", which earned Farhadi the Silver Bear for best director at the Berlin film festival, before reuniting for "The Salesman".

The daughter of a former Iranian international footballer, Alidoosti has long been seen as a champion of women's and civil rights in Iran.

On November 9, she posted an image of herself without a headscarf, holding a paper with the words "Woman, life, freedom", the main slogan of the protests.

Alidoosti had in a social media post vowed not to leave Iran and said she was prepared to "pay any price to stand up for my rights".

Her Instagram account with more than eight million followers has been inaccessible since her arrest.

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," she wrote on Instagram.

A second protester, Majidreza Rahnavard, 23, was hanged in public on December 12 and activists fear more risk execution.

The judiciary's Mizan Online news agency had said the actor was arrested as she "did not provide documentation for some of her claims" about the protests.

It complained that "a number of celebrities" had been publishing "provocative material in support of the street riots".

The Oslo-based monitor Iran Human Rights said Iran's security forces had killed at least 476 people in the protests, which Iranian officials generally describe as "riots".