Egypt's Tahrir Square has seen nearly hundred women falling victim to "rampant" sexual attacks during the past four days of protests against President Mohamed Morsi, Human Rights Watch (HRW) said.

The global rights watchdog said on Wednesday that the mobs sexually assaulted "and in some cases raped at least 91 women" in Tahrir Square amid a climate of impunity.

Citing figures of the Egyptian Operation Anti-Sexual Harassment/Assault, that runs a hotline for victims of sexual assault, HRW said that there were 46 such attacks against women on Sunday, 17 on Monday and 23 on Tuesday.

Another women's rights group, Nazra for Feminist Studies, reported that there were five similar attacks on Friday, said HRW.

Sexual harassment has long been common in Egypt, but its increasing occurrence and ferocity has shaken the protest movement. A large number of women had fallen victim to gang assaults too in the square - the epicenter of 2011 revolution.

Security vacuum

Some say the attacks are staged by thugs who are abusing a security vacuum and confident of escaping prosecution. Others say the assaults are organised to scare women off from joining protests and to stain the image of the anti-government demonstrations.

"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," said Joe Stork, HRW's deputy Middle East director.

HRW also called on Egyptian officials and political leaders "across the spectrum to condemn and take immediate steps to address the horrific levels of sexual violence" in the iconic square.

"These are serious crimes that are holding women back from participating fully in the public life of Egypt at a critical point in the country's development,” the New York-based watchdog said.

Several women required surgical intervention after the attacks, some were "beaten with metal chains, sticks, and chairs, and attacked with knives," HRW said.

HRW said the attackers needed to be brought to justice but "the government response has been to downplay the extent of the problem or to seek to address it through legislative reform alone."