Violent clashes have erupted during protests against the authoritarian government in Iran.

In the city of Karaj in the west of the capital Tehran, demonstrators and security forces clashed on Thursday, eyewitnesses reported.

There were reports of casualties on both sides.

Crowds poured into the streets - mostly women.

Cries like "we fight, we die, we don't endure any humiliation" could be heard again and again, as the witnesses reported.

Security forces are said to have shot at the demonstrators and used tear gas.

Some fought back.

The protests on Thursday marked the end of the 40-day mourning period following the death of young Iranian woman Hadis Najafi, who was reportedly shot dead by security forces during protests in Karaj in September.

The authorities deny this.

Najafi is now one of the symbolic figures of the protests.

A mourning period of 40 days is customary in Islam.

"When you see how the family suffers from the death of their daughter, you get angry," said an eyewitness on the sidelines of the demonstration.

Amnesty: at least 66 people killed

A high Islamic dignitary has been killed in Zahedan, one of the hotspots of anti-government protests.

The spiritual head of a Shia mosque was shot dead in the city, the Irna news agency reported on Thursday.

"A special unit has been set up to identify and arrest the perpetrators," said Sistan-Balochistan Province Police Commander Ahmad Taheri.

The most serious clashes between security forces and demonstrators in recent weeks have occurred in Zahedan.

According to Amnesty International, security forces killed at least 66 people there on September 30.

Zahedan is predominantly Sunni, but in Iran Shia make up the overwhelming majority of the population.

A high-ranking Sunni cleric had criticized the actions against demonstrators and said that those responsible for the state and Iran's spiritual leader, Ayatollah Ali Khamenei, would have to answer to God for it.

The mass demonstrations were triggered by the death of another young woman, the 22-year-old Iranian Kurd Mahsa Amini.

The vice squad arrested her in mid-September for allegedly violating Islamic dress codes.

She then died in police custody.

Since then, tens of thousands have taken to the streets against the Islamic Republic's repressive policies.

According to human rights activists, more than 280 people have been killed since then and more than 14,000 arrested.