He said that Iran is in a "full-fledged human rights crisis" as authorities clamp down on anti-regime dissidents, reported CNN.

The Islamic Republic has been gripped by a wave of anti-government protests sparked by the death of Mahsa Amini, a 22-year-old Kurdish-Iranian woman detained by the morality police in September allegedly for not wearing her hijab properly.

Turk called for "independent, impartial and transparent investigative processes" into violations of human rights in Iran during a special session of the UN Human Rights Council, reported CNN.

Authorities have unleashed a deadly crackdown on demonstrators, with reports of forced detentions and physical abuse being used to target the country's Kurdish minority group.

In a recent CNN investigation, covert testimony revealed sexual violence against protesters, including boys, in Iran's detention centres since the start of the unrest.

Security forces have reportedly responded to protests by using lethal force against unarmed demonstrators and bystanders who posed "no threat," Turk said to the 47-member states council in Geneva.

More than 14,000 people, including children, have been arrested in connection with the protests, according to Turk. He said that at least 21 of them currently face the death penalty and six have already received death sentences, reported CNN.

The unprecedented national uprising has taken hold of more than 150 cities and 140 universities in all 31 provinces of Iran, Turk added.

"We received reports that injured protesters fear going to the hospital for risk of being arrested by security forces," he said.

"I'm alarmed by reports that even children suspected of having participated in protests are being arrested at school, hundreds of university students have been summoned for questioning, threatened or suspended in part from entering university campuses," said Turk.

The UN rights chief further urged Iran to fully respect the fundamental freedoms of expression, association and assembly, reported CNN.

"No society can be calcified or fossilized as it may stand at a single point in time. To attempt to do so, against the will of its people, is futile," said Turk.

Meanwhile, Tehran vehemently condemned the "appalling and disgraceful" emergency meeting by the UN Human Rights Council, just as Iran's foreign ministry announced a national committee to investigate deaths linked to the protest movement, reported CNN.

The deputy of the vice president for women and family affairs in Iran, Khadijeh Karimi, who represented Iran at Thursday's session, condemned the "politically motivated" decision of Germany to call for the session, describing it as "an orchestrated ploy for ulterior motives."

Countries such as Germany, the UK and France lack "the moral credibility to preach others on human rights and to request a special session on Iran," Karimi said.

She also defended the conduct of Iranian security forces and said the government took "necessary measures" after Amini's "unfortunate" death while in the custody of the morality police, reported CNN.

The violent response of Iran's security forces toward protesters has shaken diplomatic ties between Tehran and Western leaders.

The White House on Wednesday imposed its latest round of sanctions on three officials in Iran's Kurdish region, after US Secretary Antony Blinken said he was "greatly concerned that Iranian authorities are reportedly escalating violence against protesters."