8 killed after Iranian forces open fire on protestors in Tehran

Iranian protesters on Thursday defied a deadly crackdown by security forces against nearly six weeks of women-led protests, as Tehran vowed to punish those behind a mass shooting that killed 15 worshippers at a shrine.

In the latest violent bid to crush demonstrations sparked by the death of Mahsa Amini in police custody last month, security forces opened fire and killed "at least eight people" since Wednesday evening, according to Amnesty International.

Iran has been gripped by its biggest protests for years since Amini died on September 16, three days after her Tehran arrest by the notorious morality police for allegedly breaching the country's dress code for women.

"Iran's security forces killed at least eight people since last night as they again opened fire on mourners and protesters" in at least four provinces, Amnesty said, condemning the "reckless and unlawful use of firearms".

On Wednesday, as thousands mourned 22-year-old Amini, Iran was also rocked by an attack claimed by the Islamic State jihadist group in which, state media said, a gunman killed at least 15 people at a shrine in the southern city of Shiraz.

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Ultra-conservative President Ebrahim Raisi appeared to link the two tragedies when he declared that "the intention of the enemy is to disrupt the country's progress, and then these riots pave the ground for terrorist acts".

Raisi vowed "a severe response" over the mass killing at the Shah Cheragh mausoleum following evening prayers.

Supreme leader Ayatollah Ali Khamenei called for united efforts against the "plot" by Iran's enemies.