A video of a young woman being sexually assaulted by a gang of teenage boys on a bus in Casablanca has sparked outrage in Morocco, reigniting a bitter debate about violence against women in the Muslim country.

The video, which was posted on social media on Sunday, shows four boys sexually molesting a woman while laughing, tearing her clothes off and insulting her in Arabic.

The woman – who the authorities said had learning difficulties – is seen in tears, crying for help, while neither the bus driver nor any of the passengers intervene.

Sexual harassment and abuse of women is rife in Morocco where a national survey found that nearly two-thirds of women had experienced physical, psychological, sexual or economic abuse.

Earlier in August a video showing a mob of men hounding a young woman on a street in Tangier caused uproar in the media.

On Monday the Moroccan authorities said they had arrested six boys aged 15 to 17 for their “presumed implication in the woman’s aggression” and put them under investigation.

While the video sparked widespread condemnation on social and local media, some users accused the woman of having “provoked the men with indecent clothing”.

One man wrote on Facebook that “I condemn the act but cover yourselves up, this one was easy to undress.”

Moroccan charity Don’t Touch My Child called for any witnesses to come forward “to bring to justice this barbaric horde who shamefully attacked a young women”.

Public transport company M’Dina Bus condemned the incident and said it was collaborating with authorities in the north African kingdom, which is trying to attract investors and tourists by presenting itself as a safe haven.