Eight prisoners died as a result of a fire at Tehran’s Evin prison over the weekend, Iran’s judiciary said on Monday, doubling the death toll from a blaze that has increased pressure on the government as it struggles to contain mass protests.

Iran’s judiciary said the blaze on Saturday evening was started by prisoners in a workshop after a fight, and that those killed had died of smoke inhalation. All were from a section of the prison for inmates jailed for robbery-related crimes, it said.

Evin, which in 2018 was blacklisted by the US government for “serious human rights abuses”, holds political prisoners and many detainees facing security charges, including Iranians with dual nationality.

Iran’s top judge Gholamhossein Mohseni Ejei blamed the fire on “agents of Iran’s enemy”, while the foreign ministry said such an event could have happened in any country.

The fate of Mahsa Amini, a 22-year-old Kurdish-Iranian woman who died in custody on September 16 after she was apprehended by Iran’s morality police for “inappropriate attire”, unleashed a wave of protests that spread rapidly and to all layers of society.

The unrest has turned into one of the boldest challenges to Iran’s clerical rulers since the 1979 revolution, with protesters calling for the downfall of the Islamic Republic, even if the protests do not seem close to toppling the system.

Tehran’s tough crackdown on protests which include people from all layers of society has drawn sharp international criticism from the United States and other Western powers.

Apparently opening up another new channel of foreign pressure, several European Union countries called on Monday for sanctions against Iran over the transfer of Iranian drones to Russia.

Ukraine has reported a spate of Russian attacks with Iranian-made Shahed-136 drones in recent weeks, and on Monday, Russia attacked Ukrainian cities with drones, killing at least four people in an apartment building in downtown Kyiv during the morning rush hour.

Ukraine said the attacks were carried out by Iran-made “suicide drones” and said Tehran was responsible for the “murders of Ukrainians”.

Iran denies supplying drones to Russia since its invasion of Ukraine. The Kremlin has not commented.

Iran has accused countries who have expressed support for the protests of meddling in their internal affairs, including President Ebrahim Raisi, who on Sunday blamed his US counterpart for inciting “chaos, terror, and destruction” in Iran.

One traffic police officer was shot on Monday in Saravan in southeastern Iran by what the province’s police commander said were “terrorists” armed with AK-47 assault rifles.

The sounds of gunfire were frequently heard in the Kurdish city of Sanandaj, according to audio files that human rights group Hengaw received.

A dozen young men in a key historical street of the city of Isfahan demonstrated on Monday, shouting “death to the dictator”, a popular slogan that refers to Supreme Leader Ayatollah Ali Khamenei.

At the University of Mazandaran, in northern Iran, dozens of female students on Monday were heard calling for their professors to back the protests, a video shared on social media showed.

Kurdish region

The protests, which started at Amini’s funeral in her Kurdish hometown of Saqez, spread rapidly to cities and provinces across Iran, a country of more than 80 million people.

Demonstrations resumed early on Monday in the central city of Yazd and several other cities, including Piranshahr in the northwest and Tehran.

The widely followed activist Tasvir1500 Twitter account carried a video showing people setting tires on fire in the streets and calling for the death of Khamenei.

Reuters could not independently verify the videos.

Much of the crackdown by security forces has focused on the northwest where most of Iran’s estimated 10m Kurds live, but the protests have swept other areas home to ethnic minorities with long-standing grievances against the state.

Iran’s religious leaders have said the unrest is part of a breakaway uprising by the Kurdish minority, threatening the nation’s unity rather than its clerical rule.

Iran has deployed the Basij militia, voluntary military troops which have been at the forefront of repressing popular unrest, but they have failed to take control.

The elite Revolutionary Guards, who have not taken part in the crackdown, began military exercises on Monday.

Rights groups said at least 240 protesters had been killed, including 32 minors. Over 8,000 people had been arrested in 111 cities and towns, Iranian activist news agency HRANA said on Saturday. The authorities have not published a death toll.

Iran, which has blamed the violence on enemies at home and abroad, denies security forces have killed protesters. State media said on Saturday at least 26 members of the security forces had been killed by “rioters”.