Image copyright Unknown Image caption The image of the young woman was posted on social media a day before the protests began

A woman who became the face of protests in Iran last December is the subject of a new social media campaign in the country.

Images of the woman, whose name remains unknown, defiantly taking off and waving her white headscarf - a punishable offence - in central Tehran were shared thousands of times during anti-establishment protests at the end of last year.

Now, Iranians are asking: Where is she?

On Monday, earlier reports that the female protester was arrested on 27 December were confirmed to BBC Persian by human rights lawyer Nasrin Sotoudeh, who added the protester is 31 years old and mother to a 20-month-old child.

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Mrs Sotoudeh, herself a former political prisoner, was the first rights activist to reveal more information about the young woman.

"Our investigations confirm that the young woman, whose name we still do not know, was arrested on that very same day," she wrote on Facebook on Sunday, along with a picture from the same location where the woman was first arrested.

"She was released shortly afterwards but was arrested once again," Mrs Sotoudeh added.

Since January 17, a hashtag in Persian asking just that - and English-language equivalents #where_is_she and #WhereIsShe - have been used more than 28,000 times on Twitter, as well as on other social media channels used in the country where dissent is often met with repression.

The photograph of the woman was first widely used in connection to the White Wednesday campaign in which women in Iran wear white to protest the country's strict dress code.

Since the Iranian revolution in 1979, women have been forced to cover their hair according to Islamic law on modesty, and to wear knee-length over shirts.

The unknown woman was propelled to international fame as her image became emblematic of the recent unrest, the largest since 2009, in which at least 20 people died protesting government corruption, unemployment and the weak economy.

Media playback is unsupported on your device Media caption Iran protests: Why people are taking to the streets

Rumours circulated in December and early January that she was arrested, with concerned Iranians once more using social media to find out more about her fate.

Activist and journalist Masih Alinejad, who founded the White Wednesdays campaign, tweeted the Persian hashtag and a video of herself in the United States without a hijab and waving white material on Saturday.

"If I protested like this in Iran I'd be arrested for sure. Today I echo the voices of millions of Iranian women who'd face punishment for their objection to compulsory hijab," she wrote.

A tweet by Iranian-born Canadian blogger and secular podcast host Armin Navabi asking about the fate of the protester was liked more than 2,000 times and retweeted 2,000 times.

Journalist Negin Ragh also posted a drawing made on an Iranian banknote of a woman waving a cloth, reminding social media users not to forget about unnamed woman.