The United Nations Secretary-General has called on Iran to refrain from using “unnecessary or disproportionate force” against protesters as unrest over a young woman’s death in police custody spread across the country.

Antonio Guterres called for a swift and impartial investigation by authorities into the death of 22-year-old Mahsa Amini, which has sparked unrest across Iran’s provinces and the capital of Tehran.

“We are increasingly concerned about reports of rising fatalities, including women and children, related to the protests,” UN spokesman Stephane Dujarric said in a statement on behalf of Mr Guterres.

“We underline the need for prompt, impartial and effective investigation into Ms Mahsa Amini’s death by an independent competent authority.”

Protests have spread across at least 46 cities, towns and villages in Iran. State TV reported that at least 41 protesters and police have been killed since the demonstrations began on September 17.

An Associated Press count of official statements by authorities tallied at least 14 dead, with more than 1,500 demonstrators arrested.

The New York-based Committee to Protect Journalists (CPJ), meanwhile, said it documented the arrests of at least 23 journalists as the clashes between security forces and protesters escalated.

The CPJ called on Iranian authorities to “immediately” release arrested journalists who covered Ms Amini’s death and the subsequent protests.

Mr Dujarric added that Mr Guterres had stressed the need to respect human rights, including freedom of expression, peaceful assembly, and association during the meeting with Iranian President Ebrahim Raisi on September 22.