The daughter of former Iranian President Akbar Hashemi Rafsanjani, who is a rival of President Mahmoud Ahmadinejad, was detained during an opposition rally in Tehran on Saturday, an Iranian news agency said on Sunday.

Fars News Agency, citing a security official, said Faezeh Rafsanjani and some other relatives had attended the protest and were detained in order to "preserve their security from terror acts of rioters."

It said they were transferred to the nearest military base and were kept there until the end of the unrest, suggesting they had been released. Last week, the same news agency said Faezeh and her brother Mehdi had been barred from leaving Iran.

Faezeh addressed supporters of defeated presidential candidate Mirhossein Mousavi last Tuesday when they gathered near the state television building in Tehran in defiance of a ban on opposition protests.

Rafsanjani, who remains a powerful figure in Iran, supported Mousavi in the June 12 election. Official results showed Ahmadinejad won by a landslide but Mousavi says the vote was rigged, a charge the authorities reject.

Rafsanjani reacted furiously when Ahmadinejad accused him on television of corruption, publicly urging Iran's Supreme Leader Ayatollah Ali Khamenei to rein in the president.