The UN's rights chief has demanded an end to the "unnecessary" use of force against protesters in Iran, at an urgent meeting of the Human Rights Council.
The UN's top rights body was holding a specially-convened session to discuss whether to launch a high-level international investigation into the deadly crackdown on mass protests rocking Iran.
Volker Turk, in his first appearance before the council since taking up his role, said Iran was mired in a full-fledged human rights crisis.
"The unnecessary and disproportionate use of force must come to an end," he said.
"The old methods and the fortress mentality of those who wield power simply don't work. In fact, they only aggravate the situation. We are now in a full-fledged human rights crisis."
Mr Turk said people from across Iranian society were clamouring for change, showing incredible courage.
"I urge the government and those in power to listen," he said.
"The security forces... have used live ammunition, birdshot and other metal pellets, tear gas and batons," he added.
"According to reliable sources, a conservative estimate of the death toll so far stands at over 300, including at least 40 children. This is unacceptable," Mr Turk said.
"From what we could gather, around 14,000 people, including children, have so far been arrested in the context of the protests. This is a staggering number."
He said that according to official sources, at least 21 people arrested in the context of the protests currently face the death penalty, of which at least six have been sentenced to death on charges of enmity against God and corruption on Earth.
Mr Turk said statements had sought to delegitimise the protesters and label them as agents of enemies and foreign states.
"That's a convenient narrative. As we have seen throughout history, it's the typical narrative of tyranny."
Turk said persistent impunity for human rights violations remained one of the major challenges in Iran, further fuelling discontent and distrust.
"I therefore call for independent, impartial and transparent investigative processes into alleged violations of human rights, consistent with international standards," he said.
"I call on the authorities immediately to stop using violence and harassment against peaceful protesters," Turk added.
"And to release all those arrested for peacefully protesting, as well as --crucially -- to impose a moratorium on the death penalty.
"Change is inevitable. The way forward is meaningful reforms."