Iranian authorities Saturday prevented the family of Mahsa Amini from holding a ceremony to commemorate the first anniversary of her death, confining her father under "house arrest", as sporadic protests erupted nationwide despite heavy security, rights groups said.

Amini, a 22-year-old Iranian Kurd, died a few days after her arrest by religious police for allegedly violating the strict dress code for women in force since shortly after the 1979 Islamic Revolution.

Her family says she died from a blow to the head but this is disputed by Iranian authorities.

Anger over her death rapidly expanded into weeks of taboo-breaking protests which saw women tearing off their mandatory headscarves in an open challenge to the Islamic republic's system of government under supreme leader Ayatollah Ali Khamenei.

Mahsa Amimi's father Amjad was detained early Saturday as he left the family home in the western town of Saqez, and then released after being warned not to hold a memorial service at her graveside, the Kurdistan Human Rights Network (KHRN), 1500tasvir monitor and Norway-based Iran Human Rights (IHR) said.

"Amjad Amini is under house arrest... Security forces are preventing him from visiting his daughter's grave," said IHR.

Official news agency IRNA denied the reports of the father's brief detention, and later said security forces had foiled an assassination attempt against him.

Amjad Amini had been summoned by intelligence officials last week after his announcement he planned to hold a memorial ceremony.

One of Amini's uncles, Safa Aeli, was detained in Saqez on Sept. 5 and remains in custody.