U.N. human rights chief Volker Turk urged Iranian authorities to halt "unnecessary and disproportionate' use of force against protesters.
Speaking at a session of the U.N. Human Rights Council in Geneva on Thursday, Turk said Iran was in a "full-fledged human rights crisis."
Turk expressed his support for an investigation into Iran's crackdown against protests that began two months ago after the death in police custody of 22-year-old Mahsa Amini.
'Accountability is a key ingredient of the pursuit of justice for human rights violations,' Turk said.
He told the council that authorities have used live ammunition, tear gas and batons against protesters, and that more than 300 people have been killed since the demonstrations began.
Iran's representative at the council called the debate about an investigation disgraceful and appalling.
Some information for this report came from Agence France-Presse and Reuters .