Injy Ghozlan, a member of Op Anti-Sexual Harassment/Assault, said the group has detected 46 incidents of sexual assault on protesters in Tahrir on Sunday, describing the assaults as "major and shocking."
Some of the assaulted victims required immediate medical intervention, while others required psychiatric assistance.
The initiative's volunteers, who belong to 12 rights organisations and anti-harassment initiatives, were in Tahrir from 7PM until 2AM, she told Al-Masry Al-Youm, adding that the number of reported assaults have increased compared to past protests.
Ghozlan said that the harassers used the same methods as in past attacks and that there are certain spots, such as Mohamed Mahmoud Street, where such incidents tend to happen.
Meanwhile, Fathy Farid, coordinator of Shoft Taharosh, or the "I saw harassment" initiative, held the regime responsible for the attacks, saying Tahrir has seen systematic crimes against humanity.
Farid added that "the violations committed against women have increased in number and developed in such a way that the harassers now target females who are accompanied by males."
On its Facebook page, Op Anti-Sexual Harassment/Assaults said its volunteers would be in Tahrir on Monday at 5PM and that it is accepting new volunteers.
The group said men carrying batons were seen beating women at the entrance to the metro station near the Kentucky Fried Chicken restaurant. The group added that Gameat al-Dowal al-Arabiya Street and Qasr al-Nil bridge are among the most dangerous spots for women.
Members of the initiative had received reports of 19 incidents of gang harassment during the protests marking the second anniversary of the revolution, some of which had involved attempted murder or had caused permanent disabilities. The initiative said it had intervened in 15 of those incidents.
The Free Egyptians Party said it observed a campaign of "organized sexual harassment" in Tahrir Square during the 30 June protests against President Mohamed Morsy, and described the attacks as "the regime's failed attempt to stay in power after having lost all legitimacy.”
In a statement Monday, the party warned against attempts to "terrify" women, smear the revolution, and intimidate protesters. It stressed that women played a vital role in the peaceful demonstrations.
Sexual harassment is not uncommon in the streets of Cairo. A 2008 report by the Egyptian Center for Women's Rights found that two-thirds of women in Egypt experience sexual harassment on a daily basis.
Edited translation from Al-Masry Al-Youm