A video of anti-riot forces in Iran sexually assaulting a female protester whilst trying to arrest her has provoked fury on social media.

Users voiced outrage, with many calling for "justice" and the resignation of the police chief. Some pro-government users also condemned the perpetrators.

Despite blocks on some social media tools, Iranians are still managing to share powerful images of the protests.

The country has been rocked by the most intense unrest in decades.

The protests erupted last month when anger over the death in police custody of 22-year-old Kurdish Iranian Mahsa Amini boiled over. Officials say she died from an underlying health condition, but her family said she died after being beaten by morality police.

Numerous videos of the protest have gone viral both inside and outside of Iran. This latest video, which happened in Tehran's Argentina Square on Wednesday, shows a group of officers in protective gear and helmets surrounding a woman on a main road.

One of them grabs her by the neck and leads her into a crowd of about two dozen police, many of whom are on motorcycles.

While the woman is being forced towards one of the bikes, another officer approaches her from behind and puts his left hand on her bottom.

The woman then crouches on the ground as more officers surround her. A female voice behind the camera is heard saying: "They are pulling her hair."

Drivers in vehicles next to where it is happening start sounding their horns, a form of protest in similar situations seen in the past few days across the country.

The woman, who appears to have no hijab, or headscarf, is then seen standing up and running away from the scene.

At this point, the same voice on the clip is heard to say: "Look at him [the security force officer], he is laughing".

Tehran's Police Public Relations office has said the incident is being investigated, state news agency Irna reported.

The police statement does not give details of what happened, but says that "enemies using psychological warfare tried to cause public anxiety and incite violence".

The fact that the incident happened in public has led human rights activists to question what security forces might also be doing behind closed doors.

"Have you brought out the harassment of the girls of this land from [your] prisons into the open streets with the aim to shout out [at us] in public your obscenity, lechery and filth?" posted a social media user by the name of Atefeh.

Mistreatment, including sexual and psychological abuse, has been reported by many inmates, especially political prisoners, for years.

Many Iranians commented on social media that the video from Tehran had made them more determined to go out on the streets to protest, with one person saying they intended "to put their anger and fury into action". (BBC)

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