Opposition leader Mir-Hossein Moussavi, one of the candidates who lost in the June 12 election to President Mahmoud Ahmadinejad, and former presidents Akbar Hashemi-Rafsanjani and Mohammad Khatami had several times called on the relevant officials to release all political detainees.

Moussavi had even accused the security officials of treating the prisoners like those during the Shah's era.

In a statement issued on his website, Moussavi termed the killings and arrests of the protesters as a catastrophe and said 'people would never forget those elements behind these crimes'.

The order by the judiciary chief was considered the first victory for Moussavi and the opposition, especially after many parliament deputies, in the meantime, have voiced concern about the situation of the detainees.