Police investigate 27 complaints from Sunday’s rallies as sexual violence continues to grow.

CAIRO — A string of sexual assaults on women during celebrations of Egypt’s presidential inauguration – including a mass attack on a 19-year-old student who was stripped in Cairo’s Tahrir Square – prompted outrage Monday as a video emerged purportedly showing the teenager, bloodied and naked, surrounded by dozens of men.

Seven men were arrested in connection with the assault and police were investigating 27 other complaints of sexual harassment against women during Sunday’s rallies by tens of thousands of people celebrating Abdel-Fattah el-Sissi’s inauguration late into the night, security officials said.

Sexual violence has increasingly plagued large gatherings during the past three years of turmoil following the 2011 uprising that ousted autocrat Hosni Mubarak, and women’s groups complained Monday that tough new laws have not done enough.

Twenty-nine women’s rights groups released a joint statement accusing the government of failing do enough to address the spiraling outbreak of mob attacks on women. The groups said they had documented more than 250 cases of “mass sexual rape and mass sexual assaults” from November 2012 to January 2014.

“Combating that phenomena requires a comprehensive national strategy,” said the statement signed by the women’s groups.

Sexual harassment has been one of Egypt’s enduring social ills, embedded in the country’s patriarchal conservative culture, where women are seen as inferior to men.

Sexual assaults have increased dramatically in ferocity and in number in the three years since Mubarak’s ouster, with Tahrir square, birthplace of the 2011 uprising, the site of multiple sexual attacks on women amid the large crowds.

In the latest incident, video footage posted on social media purportedly shows the student completely naked amid a crowd of men, parts of her body bloodied as policemen struggled to escort her out of Tahrir.

Seven men were arrested in connection with the attack on the student, who was hospitalized, said the officials.

The Interior Ministry, in charge of police, identified the seven suspects and gave their ages as between 15 and 49. It said they were arrested for “harassing several girls” but made no mention of the student.

Authorities investigating other reports of sexual assaults were examining a dozen videos from security cameras or from bystanders who filmed the incidents on their mobile phones, the officials said.

They said the footage suggested organized attacks, with groups of men luring victims away from densely crowded spots before encircling them as they assaulted them. Many brandished knives which they used to threaten victims or against anyone attempting to come to their rescue.