DUBAI: Protesters in Tehran and several other Iranian cities torched police stations and vehicles on Thursday as unrest triggered by the death of a woman detained by the Islamic Republic's morality police intensified for a sixth day.

Mahsa Amini, 22, died last week after being arrested for wearing "unsuitable attire" by the morality police in Tehran. She fell into a coma while in detention. The authorities have said they would launch an investigation into the cause of death.

Amini's death unleashed huge anger in the population and the worst protests in Iran since 2019. Most have been concentrated in Iran's Kurdish-populated northwestern regions but have spread to the capital and at least 50 cities and towns nationwide, with police using force to disperse protesters.

In the northeast, protesters shouted "We will die, we will die but we'll get Iran back" near a police station which was set on fire, a video showed that was posted on a Twitter account 1500tasvir, which focuses on Iran protests and has around 100,000 followers.

Reuters could not verify the footage.

Another police station was set ablaze in the capital Tehran as the unrest spread from Kurdistan, the home province of Amini.

Iran's rulers fear a revival of the 2019 protests over gasoline price rises, the bloodiest in the Islamic Republic's history. Reuters reported 1,500 were killed.

Protesters also expressed anger at Iran's Supreme Leader Ayatollah Ali Khamenei. "Mojtaba, may you die and not become Supreme Leader," a crowd was seen chanting in Tehran, referring to Khamenei's son, who some believe could succeed his father at the top of Iran's political establishment.

Reuters could not verify the video.

Reports from Kurdish rights group Hengaw, which Reuters could not verify, said three protesters were killed by security forces on Wednesday, bringing the death toll to 10. Officials have denied that security forces have killed protesters, suggesting they may have been shot by armed dissidents.

With no sign of the protests easing, authorities restricted access to the internet, according to accounts from Hengaw, residents, and internet shutdown observatory NetBlocks.

Amini's death has unleashed fury across Iran over issues including freedoms in the Islamic Republic and an economy reeling from sanctions.

Women have played a prominent role in the protests, waving and burning their veils, with some cutting their hair in public.

In northern Iran, crowds armed with batons and rocks attacked two members of the security forces on a motorbike as a crowd cheered, as seen on a video, which Reuters was unable to verify.