Iranian security forces released Mahsa Amini's father on Saturday after briefly detaining and warning him against marking the anniversary of her death, a human rights group said.

"Security forces detained Amjad Amini today and returned him to his house after threatening him against marking his daughter's death anniversary," the Kurdistan Human Rights network said.

Mahsa Amini's death in police custody a year ago unleashed months of anti-government protests that spiralled into the biggest show of opposition to the authorities in years.

Iranian officials were not immediately reachable by Reuters for comment