The United States on Friday expressed concern about a rise in sexual violence and gang rapes in Egypt and condemned local politicians who have said the women are to blame.

The response came after a string of reports by AFP and other media outlets about women who are speaking out about rape and other sexual attacks inflicted by groups of men at demonstrations in the wake of the 2011 uprising.

The same reports have quoted ultra-conservative Egyptian Islamists as saying the women are asking for such attacks because they mingle with men in public.

White House deputy spokesman Joshua Earnest said President Barack Obama's administration has seen the reports and is "deeply concerned."

"Sexual violence, including gang rapes, has occurred during recent demonstrations in Egypt," Earnest told reporters aboard Air Force One.

"This is a cause of great concern to the United States, the international community and to many Egyptians. These victims are the mothers, wives, daughters and sisters of Egypt."

Earnest said the Egyptian government should take measures to prevent sexual violence and to prosecute those involved.

"The idea that some Egyptians are blaming the victims for being raped and assaulted is abhorrent.

"We strongly condemn these views and reaffirm the right of women to express themselves in public squares alongside men, as well as the responsibility of the Egyptian government to protect them."

Egypt has been rocked by demonstrations in recent months in which protesters opposed to President Mohamed Morsi -- a former senior Muslim Brotherhood figure elected last year -- clash with police and supporters of the Islamist group.

The demonstrations frequently turn violent, and several women have been assaulted by mobs of young men in and around Cairo's central Tahrir Square, epicenter of the uprising that toppled Hosni Mubarak in February 2011.

The attackers have stripped women of their clothes with knives, beaten them and penetrated them with their fingers.

On January 25, as thousands of Egyptians marked the second anniversary of the uprising, at least 19 women were assaulted, according to Operation Anti Sexual Harassment, one of several groups formed to try to stop the attacks.

Foreigners reporting on the demonstrations have also been targeted, including well-known CBS correspondent Lara Logan, who was sexually assaulted by a mob in Tahrir Square the night Mubarak was forced to step down.

The latest US travel warning for Egypt notes "a rise in gender-based violence in and around protest areas" and says that while Americans have not been targeted for their nationality, they should avoid all demonstrations.