CAIRO — Washington’s envoy on human rights cautioned Tuesday against the failure of Egypt’s government to identify the perpetrators behind a growing number of gruesome attacks against female protesters, as nearly 1,000 women gathered in Cairo to denounce the recent sexual assaults.

Beating drums and blowing whistles, the women defied advice by some lawmakers that suggested their presence in Tahrir Square, the focal point of protests, was the reason for the mob attacks.

“A woman in the square is a revolution, but your words Afifi are shameful,” read one banner in response to Adel Afifi, a member of the Islamist-dominated interim parliament, who said this week that women are subjecting themselves to attacks by mixing with men in unsafe places.

While sexual harassment of women has long been a problem in Egypt, dozens of violent attacks have been reported specifically in and around Tahrir Square since the fall of longtime autocrat Hosni Mubarak two years ago. Hundreds of unidentified men have taken part in attacks on women, ripping their clothes off, touching them and, in one case, raping a 19-year-old with a blade.

The U.S. Assistant Secretary of State for Democracy, Human Rights and Labor, Michael Posner, criticized what he said was the failure of Egypt’s criminal justice system to identify and bring to justice perpetrators “involved in an alarming number of rapes and other acts of violence against women.”

In meetings with Egyptian officials, including the foreign and justice ministers, as well as one of the president’s advisers and the nation’s top cleric, Posner said he expressed Washington’s concern that the rights of women are not being prioritized alongside other key issues such as transparency, rule of law and building a better climate for civil society.

Male and female civilian volunteers offered to guard the women’s rally Tuesday. A similar rally was attacked by mobs in June, despite the presence of volunteer guards.

Monelle Janho, a 47-year-old mother of two and French teacher, said she no longer leaves her house without a stun gun because of the increased levels of violence.

“We will resort to violence if we have to,” she said. “We are here and are not seeking violence, but we want the Egypt we know back,” she said.

Electrical engineer Manal al-Malla, 42, said she has taken part in more protests, not fewer, after harassment increased.

“We will continue to defend our freedom and dignity,” she said.

Other rallies in solidarity with women in Egypt were scheduled to take place around the world Tuesday.

They come after lawmakers in the Shura Council, or upper house of parliament, recently suggested women should have a designated space for protesting in Tahrir Square in order to avoid repetitive sexual attacks against them.