Iranian security forces have killed 72 people, including 56 in Kurdish-populated areas, in the past week alone in their crackdown on the protests sparked by Mahsa Amini's death, a rights group said Tuesday.

The protests, which erupted in mid-September following the death of Amini, 22, in the custody of the morality police, have turned into the biggest challenge for Iran's clerical leadership since the 1979 Islamic revolution.

With the wave of protests cutting across ethnicities, social classes and provincial boundaries, authorities have responded with an intensifying crackdown that has sparked an international outcry.

Iran has also launched repeated cross-border missile and drone strikes, most recently Tuesday, against exiled Kurdish opposition groups it accuses of stoking the protests from their bases in neighbouring Iraq.

Norway-based group Iran Human Rights (IHR) said in its latest toll on the violence inside Iran that 416 people had been killed by security forces nationwide, including 51 children and 21 women.

It said 72 people had lost their lives in the past week alone, including 56 in western Kurdish-populated areas where there has been an upsurge in protest activity over recent days.

Several towns in Kurdish-populated western Iran, including Mahabad, Javanroud and Piranshahr, have seen large protests, often starting at the funerals of those previously killed in the demonstrations.

The Norway-based Hengaw rights group, which focuses on Iran's Kurdish areas, has accused Iranian security forces of directly firing on protesters with machine guns and shelling residential areas.

Internet blackout

Hengaw said that five people were killed in Javanroud on Monday alone after thousands gathered for funerals for victims of the crackdown who were killed at the weekend.

The group said it had confirmed the killing of 42 Kurdish citizens of Iran in nine cities over the last week, almost all killed by direct fire.

Monitors also accused Iran of imposing a nationwide mobile internet blackout on Monday at the height of the protest activity.

Monitor Netblocks said Tuesday that the mobile internet had now been restored after a "3.5 hour cellular data blackout" which also coincided with the refusal of Iran's football team to sing the national anthem in the World Cup.

Freedom of expression group Article 19 expressed alarm that "reports of extreme state brutality continue out of Kurdistan alongside nationwide internet disruptions and shutdown".

Hengaw meanwhile posted a video of protesters trying to remove birdshot pellets from the body of a protester with a knife, saying people were afraid to go to hospital for fear of being arrested.

'Systematic killing'

The New York-based Center for Human Rights in Iran on Monday urged the international community to act to prevent a massacre in the area.

"Unless Islamic republic authorities decide the costs of massacring civilians to crush the ongoing protests in Iran are too high, they will continue to slaughter children, women and men with impunity in a desperate attempt to reassert control," said CHRI director Hadi Ghaemi.

According to figures collated by IHR, over half of those killed by the Iranian security forces in the crackdown have died in provinces populated by ethnic minorities.

It said 126 people had been killed in the southeastern province of Sistan-Baluchistan, largely populated by the Sunni Baluch minority, where the protests had a separate spark but fed into the nationwide anger.

Meanwhile 48 people have been killed in Kurdistan, 45 in West Azerbaijan and 23 in Kermanshah regions with a strong Kurdish presence, it said.

"Systematic killing of civilian protesters belonging to the Kurdish and Baluch minorities amounts to crimes against humanity," said IHR director Mahmood Amiry Moghaddam.

The mainly Sunni Kurds, often described as one of the world's largest stateless peoples, make up one of Iran's most important non-Persian ethnic minority groups and also have significant minorities in neighbouring Iraq and Turkey as well as Syria.