'Iran's obligations under international human rights treaties require the establishment of an independent and impartial judicial inquiry to determine the causes of Zahra Kazemi's death,' Amnesty International said.

'Such investigation must also determine whether Zahra Kazemi was ill-treated or tortured in custody as some reports have indicated,' the organisation added.

Zahra Kazemi, who had dual Canadian and Iranian nationality, died at the Baghiyetollah Hospital in Tehran while under guard. She was arrested for taking photographs of people protesting against the detention of family members outside the Evin prison in northern Tehran. Amnesty International has documented for years cases of ill-treatment and torture in detention.

The organisation welcomed reports that President Mohammad Khatami ordered the Ministers of the Interior, Justice, Intelligence and Culture and Islamic Guidance to investigate Zahra Kazemi's death in custody.

'The authorities must enact concrete measures aimed at ending all forms of ill-treatment in Iran, such as acceding to the UN Convention against Torture and other Cruel, Inhuman and Degrading Treatment or Punishment,' the organisation said.