Egypt's prosecution service has referred 13 men to trial for alleged sex attacks on women at Cairo's Tahrir Square, including during inaugural celebrations for new President Abdel Fattah al-Sisi.
It was the first time charges have been made in the North African country in connection with mass sexual assaults.
The attacks took place on January 25, 2013, as Egypt marked the second anniversary of the 2011 revolt, and on June 3 and June 8 this year as revellers marked Sisi's election victory and inauguration, the prosecutor general's office saidon on Saturday.
The 13 accused, including a minor, are charged with "kidnapping, raping, sexually attacking, attempting to murder and torturing the women", it said.
If convicted of the charges, the defendants could be sentenced to life imprisonment.
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Since the uprising that toppled long-time president Hosni Mubarak in 2011, the problem of sexual harassment has worsened in Egypt, with women regularly attacked during rallies by groups of men in and around Tahrir Square, the epicentre of protests.
Hundreds of women protested in Cairo on Saturday against the assaults.
Activists were outraged this week after graphic video footage of a woman being sexually assaulted at Tahrir Square went viral on YouTube, Facebook and Twitter.
The footage, apparently filmed using a mobile phone, shows a mob of men surrounding a young woman, who was stripped and badly bruised in the assault.
It was unclear whether the victim in the video was among those attacked during the pro-Sisi celebrations.
The prosecution service said police were searching for the person who recorded the video as this action was against "public morals".
Egypt, which had no specific law on sexual harassment, only recently approved penalties for such offences to include jail terms, fines or both.
