Female protesters were beaten, raped and intimidated in a post-election crackdown by the Iranian authorities. Silenced by stigma and fear, these women are now using social media to bear witness to the horror

A young woman is speaking to the camera, her face obscured to prevent her being identified. Her voice heavy with emotion, and hands gesturing, she describes the rape and torture she endured at the hands of her guards while imprisoned during the post-election crackdown in Iran. "Death was my first wish," she says after recounting the physical and sexual assaults that began when she was picked up on her way home from university and thrown into a van. "I wanted it to be over. I wanted to die."

Bruised from her beatings, she was taken to a detention centre where her interrogator told her, before he raped her: "I will do something you will never forget. I'll make it so you never want to leave your house again, so any time you hear my name, you will tremble." The young student was ordered to copy a "confession", which said she was a "rioter" and a terrorist who had endangered national security. "I didn't even have nail clippers in my purse for them to say I had anything remotely sharp or dangerous," the woman retorts. "All I had done was give one vote and that was to Mousavi. A vote that was never counted."

The 22-year-old filming her statement is one of 300 women known to have been arrested in Iran since the disputed election of June 2009, when supporters of Mir Hossein Mousavi took to the streets in protest against the re-election of President Mahmoud Ahmadinejad. Some cases, such as that of film-maker Mahnaz Mohammadi and Maryam Majd, a photojournalist, have been criticised, but most, like that of the young student, are unlikely to attract international attention. "No one came to look for me. No one knew when they were raping me, or when they were burning me with cigarettes," she says.

Few post-election detainees have spoken about about their experiences because they fear not only being re-arrested, but also the stigma of rape that exists in Iran. But social media is one way of bearing witness. The student's 100-minute testimony is the most detailed account of the treatment of prisoners in Iran since the crackdown began, says Hadi Ghaemi, executive director of the New York based International Campaign for Human Rights in Iran. A 28-minute segment of it has had more than 75,000 views and has been shared widely on social networks including Facebook and Twitter. It has opened up discussion about abuse, torture and rape of ordinary protesters, says Ghaemi, and fuelled his campaign to get the UN to hold Ahmadinejad to account for human rights abuses ahead of his appearance before the assembly in New York.

"The regime has capitalised on not only the fear of retribution but also the social and cultural attitudes towards rape," explains Ghaemi. "Two years after the post-election crackdown, the Iranian regime is intent on erasing any memory and documentation of the widespread violence it unleashed against protesters. This young woman's testimony is a brave act of defiance against this trend."

But the student is part of a younger generation of women who are more willing to challenge traditional attitudes about their position in society, says journalist and women's rights activist Parvin Ardalan. "Rape is something that is very difficult to talk about because of the attitude that exists, not only in Iran, that victims are to blame for what happens to them," she says. "But attitudes are slowly changing and women are starting to talk more. By going in front of a camera [the student] has challenged traditional thinking that if something happens to you, then you don't say anything.

"Social media gave the young woman a voice, enabling her to speak out about her experience and encourage other women on the margins to follow her example, but the power of social media on its own is not enough," says Ardalan. "We still have to challenge the fact that when people hear what happens to her they are less likely to believe her because she is a woman, or that she might still be blamed for what happened to her."

While victim-blaming is a problem women face around the globe, the consequences for women who speak out about rape can be deadly. Rana Husseini, a Jordan-based journalist whose book Murder in the Name of Honour is an investigation of so-called "honour killings" around the world, says: "Some women who are victims of rape could face extreme punishments that could lead to death not only because of the negative societal view of women who are raped, but because of the fact that they have lost their virginity in the process."

The stigma has been such a barrier to women reporting rape in Libya that women's rights activists have said it is unlikely that the true extent of sexual violence against women will ever be known. The risks women face were illustrated dramatically when Iman al-Obeidi went to a Tripoli hotel in March this year and told foreign journalists there that she had been gang-raped by Muammar Gaddafi's troops. She was later denounced as a "whore" by the state TV presenter Hala Misrati who claimed a decent family would not spread news about their daughter's rape. "With time they may even kill the girl herself," she concluded.

In Sudan, however, one woman has come forward to claim that she was kidnapped, assaulted and gang-raped by members of Sudan's National Intelligence and Security Services. Safiya Eshaq, a 25-year-old member of an anti-government youth group Grififna posted a video on YouTube earlier this year describing how she was attacked by secret intelligence police during protests in Khartoum. The fact that she did was brave enough – to do so with her face uncovered caught the attention of Sudan's media, which reported her claims. But Eshaq has since been forced to flee Khartoum and so far two journalists have been imprisoned and others are awaiting trial after they were accused of publishing Eshaq's "lies".

In Egypt, where the power of social media was harnessed so effectively in the revolution, women are using video, blogs, Twitter and Facebook both to hold the authorities to account and to challenge attitudes that keep women silent about rape and sexual harassment. The fact that women prisoners were subjected to torture and "virginity tests" when they were arrested in Tahrir Square in March came to light because women such as Salwa-Al-Housiny Gouda were prepared to make statements in public meetings that were posted on YouTube. This determination to bring issues to light is behind Harassmap, a project that utilises open-source mapping technology to allow women to report incidents of sexual harassment by sending a text message. "It enables women to share their feelings anonymously but it also helps highlight the problem more, to bring it into the media spotlight and make the issue heard," says Harassmap co-founder Engy Ghozan.

In partnership with Nazra, an organisation for feminist studies, Harassmap recently took part in a day of blogging and tweeting about sexual harassment, joining activists in Syria, Sudan and Lebanon. Both women and men took part, writing hundreds of blog posts in Arabic and English discussing the issue, commenting on a Facebook page and sending messages on Twitter using the hashtag #endSH in their tweet.

Prominent activist Manal Hassan wrote: "The worst thing abt sexual harrasment is it's always looming over u.. it's not abt something happening, it's the constant fear of it."

While the day of blogging helped raise awareness about the issue, some of the comments on Twitter suggesting that women are to blame and even encourage sexual harassment reveal the challenges ahead. "Perceptions need to change and we need to see an end to victim-blaming," says Ghozan. "The whole of society needs to start to take responsibility for the problem."

• A typographical error in the picture caption of this article was corrected on Monday 26 September. The original said that the film clip had been viewed more than "75,00" times online.