Several UN human rights experts have called on Iranian authorities to immediately stop a recent wave of journalist arrests and to release those already detained.
The experts said in a statement that security forces arrested 17 mostly independent journalists last week and raided the offices of five newspapers.
Arrest warrants were issued for several other journalists.
The group said more than 40 journalists were already imprisoned in Iran before the latest crackdown.
The UN experts include the special rapporteur on freedom of expression, the chair-rapporteur of the working group on arbitrary detention, the special rapporteur on human rights defenders, and the special rapporteur on human rights in Iran.
The group called the detentions "disturbing" and said they represented "a flagrant violation of Iran's obligations under international human rights law."