Amnesty International and UN special rapporteurs on Thursday called for a transparent probe into reports that Iranian security forces had killed and wounded dozens of Afghan migrants seeking to cross into Iran from Pakistan.

Iran hosts one of the largest refugee populations in the world, mostly Afghans who fled strife in their home country in the last decades, but the flow of Afghan immigrants has increased since the Taliban took over in August 2021.

According to local news reports and rights groups, Iranian security forces opened fire on a group of Afghans seeking to cross over the border from Pakistan into the Saravan district of Iran’s southeastern province of Sistan-Baluchistan on Sunday evening.

There have been no reports of the incident in official Iranian media. Videos posted on social media have shown images of bloodied corpses of young men in traditional clothing strewn across the road.

The Baluch rights group Haalvsh said that 300 people had attempted to cross and as many as 260 were killed. It was not immediately possible to verify this figure.

“A prompt, transparent, independent and effective investigation must be carried out into the use of unlawful lethal force, violating the right to life of Afghans,” Amnesty International said, describing the report as “horrifying”.

The UN special rapporteur on the situation of human rights in Afghanistan, Richard Bennett, wrote on X he was “seriously concerned” about the reports and urged authorities to “investigate transparently”.

“Clarity is urgently needed. These reports don’t stand in isolation. More dignity and safety is needed for Afghans worldwide,” he said.

UN special rapporteur on Iran, Mai Sato, added there was an “urgent need for investigation to gain clarity about the reports of many Afghan migrants being injured and killed.”

Iran shares a more than 900-kilometre (560-mile) border with Afghanistan and a shorter border with Pakistan to the south.

Reports last month said Iran’s military has built a wall along more than 10 kilometres (6 miles) of its border with Afghanistan in a bid to halt migrant flows with another 50 kilometres (31 miles) set to be walled off.

In September, Interior Minister Eskandar Momeni said Iran will employ other methods including barbed wire and water-filled ditches in addition to the wall to block the border.

Iranian authorities have consistently denied mistreating Aghans in Iran. President Masoud Pezeshkian has said his government plans to “repatriate illegal nationals to their country in a respectful manner”.