According to reports, Parastoo Ahmadi was detained on Saturday in Mazandaran province's Sari, which is around 280 km from Iran's capital Tehran.

A case was filed against her on Thursday after she posted her concert online.

In the concert video, she could be seen performing in a sleeveless black dress with her hair left uncovered.

She was also seen performing alongside four male musicians.

"I am Parastoo, a girl who wants to sing for the people I love. This is a right I could not ignore; singing for the land I love passionately. Here, in this part of our beloved Iran, where history and our myths intertwine, hear my voice in this imaginary concert and imagine this beautiful homeland," Ahmadi wrote in a post accompanying the video on YouTube.

The concert has garnered over 1.5 million views on YouTube.

Iranian women and girls now face prison terms of up to 15 years and possible death sentences for failing to wear a hijab, through a new strict law on religious dress and behaviour that was implemented this week.

Independent UN Human Rights Council-appointed experts said in a statement that it represents a fundamental attack on women’s rights.

The legislation, which applies to children as young as 12, combines severe criminal penalties with mandatory citizen surveillance and systematic enforcement across all sectors of society, the experts added.

The Law on Protecting the Family through the Promotion of the Culture of Chasity and Hijab, represents what experts describe as “an intensification of State control over women’s bodies in Iran and a further assault on women’s rights and freedoms”.

The new legislation expands existing restrictions, targeting women and girls who fail to wear a hijab in both physical and online spaces. While the hijab requirements were already mandatory under Iran’s Islamic Penal Code, this new law introduces dramatically harsher consequences.

Violations can now result in extended prison sentences of up to 15 years and substantially increased fines. Most concerning to human rights experts is the provision allowing judges to impose the death penalty under the charge of “corruption on earth”.