A huge fire has broken out at Iran’s notorious Evin Prison, where political prisoners and anti-government activists are kept in the capital Tehran.

Online videos and local media reported gunshots, as nationwide protests entered a fifth week.

Iran’s state-run IRNA reported that there were clashes between prisoners in one ward and prison personnel, citing a senior security official.

The official said prisoners set fire to a warehouse full of prison uniforms, which caused the blaze. He said the “rioters” had been separated from the other prisoners to de-escalate the conflict.

Iran Protests
Demonstrators hold placards outside the Iranian Embassy in London with images of the 22-year-old woman whose death in custody sparked worldwide protests (AP)

The “situation is completely under control”, the official added, and firefighters are extinguishing the flames.

Shots continued to ring out as plumes of smoke engulfed the sky in Tehran amid the sound of an alarm, videos show.

Witnesses said that police blocked roads Evin Prison and at least three strong explosions were heard coming from the area. Traffic was heavy along major motorways near the prison, which is in the north of the capital, and many people honked their horns to show their solidarity with the protests.

Riot police were seen riding on motorbikes toward the facility, as were ambulances and fire trucks. Witnesses also reported that the internet was blocked in the area.

The US-based Centre for Human Rights in Iran reported that an “armed conflict” broke out within the prison walls. It said shots were first heard in Ward 7 of the prison. The Associated Press could not immediately verify this account.

Chile Iran Protest
Iranian residents in Chile leave red handprint marks, symbolising blood, on the wall of Iran’s embassy during a protest (AP)

The prison fire occurred as protesters intensified anti-government demonstrations, sparked by the death of 22-year-old Mahsa Amini in September, along main streets and at universities in some cities across Iran on Saturday.

Human rights monitors reported hundreds dead, including children, as the movement concluded its fourth week.

Demonstrators chanted “Down with the dictator” on the streets of Ardabil in the country’s north-west.

Outside of universities in Kermanshah, Rasht and Tehran, students rallied, according to videos on social media. In the city of Sanandaj, a hotspot for demonstrations in the northern Kurdish region, school girls chanted: “Woman, life, freedom” down a central street.

The protests erupted after public outrage over the death of Ms Amini in police custody. She was arrested by Iran’s morality police in Tehran for violating the Islamic Republic’s strict dress code.

Iran’s government insists Ms Amini was not mistreated in police custody, but her family says her body showed bruises and other signs of beating after she was detained.

Chile Iran Protest
Iranian residents in Chile lie on the ground in protest over the death of Mahsa Amini (AP)

At least 233 protesters have been killed since demonstrations swept Iran on September 17, according to US-based rights monitor HRANA. The group said 32 among the dead were below the age of 18. Earlier, Oslo-based Iran Human Rights estimated 201 people have been killed.

Iranian authorities have dismissed the unrest as a purported Western plot, without providing evidence.

Public anger in Iran has coalesced around Amini’s death, prompting girls and women to remove their mandatory headscarves on the street in a show of solidarity. Other segments of society, including oil workers, have also joined the movement, which has spread to at least 19 cities, becoming one of the greatest challenges to Iran’s theocracy since the country’s 2009 Green Movement.

Riots have also broken out in prisons, with clashes reported between inmates and guards in Lakan prison in the northern province of Gilan recently.

Commercial strikes resumed on Saturday in key cities across the Kurdish region, including Saqqez, Amini’s hometown and the birthplace of the protests, Bukan and Sanandaj.

The government has responded with a brutal crackdown, arresting activists and protest organisers, reprimanding Iranian celebrities for voicing support, even confiscating their passports, and using live ammunition, tear gas and sound bombs to disperse crowds, leading to deaths.

In a video widely distributed on Saturday, plainclothes Basij, a paramilitary volunteer group, are seen forcing a woman into a car and firing bullets into the air amid a protest in Gohardasht, in northern Iran.

Widespread internet outages have also made it difficult for protesters to communicate with the outside world, while Iranian authorities have detained at least 40 journalists since the unrest began, according to the Committee to Protect Journalists.