"Horrific levels" of sexual violence and rape against women in Cairo's Tahrir Square have been reported amid protests linked to the toppling of the Egypt's president.
Human Rights Watch (HRW) is among the groups that have condemned the attacks, calling on authorities to address a "climate of impunity" after the ouster of Egypt's first freely elected president, Mohamed Mursi.
The group said it had " confirmed that mobs sexually assaulted and in some cases raped at least 91 women in Tahrir Square" during four days of protests beginning June 30.
Other reports suggested a higher number — agencies cited by Australia's Fairfax media said 101 sex attacks had occurred, several of them brutal rapes.
Operation Anti-Sexual Harassment, a volunteer vigilante group formed to physically rescue women in Tahrir Square, said some female protesters had been raped with knives and sharp objects, while others were beaten with sticks and kidnapped in vehicles.
Sex attacks were reported during the 2011 revolution that overthrew Hosni Mubarak, however this, Fairfax wrote, was "unprecedented."
HRW said there had been 46 attacks against women on Sunday, 17 on Monday and 23 on Tuesday.
HRW's deputy Middle East director, Joe Stork, said in a statement:
"The rampant sexual attacks during the Tahrir Square protests highlight the failure of the government and all political parties to face up to the violence that women in Egypt experience on a daily basis in public spaces."