Egyptian authorities have ordered the arrests of a group of men accused of being involved in a gang rape at a Cairo hotel amid a rare debate about sex crimes that started on social media and has fuelled a growing #MeToo movement.

Lack of action over the 2014 incident, that was reported to have involved six men from powerful families, caused an uproar after being disclosed in July by an Instagram account with more than 180,000 followers that aims to expose sex attackers.

The case came after the same Instagram account, Assault Police, named a university student from a wealthy family accused of raping and blackmailing multiple women. He was subsequently arrested with the case now under investigation.

The publicity over the two cases has prompted hundreds of women to share stories online of sexual violence and abuse, with women's rights activists hoping this would be a turning point for Egypt to start taking sex crimes seriously.

"The public prosecution orders the arrest of the accused in assaulting a girl in the Fairmont Hotel in 2014, placing them on travel bans," Egypt's public prosecution said in a statement.

The prosecution launched an investigation into the case this month after several people came forward to give statements about the incident after a party at the five-star hotel, leading to questioning of the victim and a number of witnesses.

The Instagram account that exposed the two cases closed after its administrators received repeated death threats but it has since been reactivated.

The state-run National Council for Women said in a statement that the public prosecution's decision sent a message of reassurance and comfort to women who have long felt disadvantaged in the conservative, Muslim-majority nation.

The 2014 incident has been one of the most controversial cases of sexual violence in recent years in Egypt where campaigners say a deep-rooted bias means women often face more blame for behaviour deemed provocative than men for sex crimes.

In what activists see as a move undercutting women's rights, prosecutors have recently charged several women for "inciting debauchery" with songs and dances in TikTok videos.

Last week Egypt's parliament gave its final approval to a law to protect the anonymity of victims of sexual harassment or assault to encourage women and girls to report such attacks without fearing social stigma.

Reda Eldanoubki, a lawyer and executive director of the Women's Center for Guidance and Legal Awareness, said if convicted the accused men could face hefty jail sentences.

"We hope that women amid this momentum would make more gains in their endeavours to be legally protected against sexual violence in all its forms," he told the Thomson Reuters Foundation.