Iranian Supreme Leader Ayatollah Ali Khamenei has granted clemency to more than 5,100 prisoners to mark a Shi'ite religious holiday, his website announced on June 26.
The statement did not identify the prisoners in question or say whether they had been released or had sentences shaved.
The leniencies were handed down in conjunction with the anniversary of the birth of Imam Reza, one of Shi'ite Islam's most sacred figures.
Amnesty International accuses Iran of routinely denying fair and open trials to the accused, carrying out arbitrary detentions, and systematically concealing the whereabouts of thousands of political dissidents "forcibly disappeared" and thought to have been extrajudicially executed decades ago.
Iranian dissidents, foreign governments, and local and international rights activists have frequently called on officials to release political prisoners in the country.
Khamenei, who holds ultimate power on religious and political affairs in Iran, issues mass clemencies on several holidays each year.