Amnesty International and Human Rights Watch are concerned about the arrests of scores of Iranian-Arab activists in Khuzestan in recent weeks.
In a report, the two rights groups maintain that between 70 and 100 activists participating in peaceful demonstrations have been arrested in Khuzestan since March.
Following the self immolation and death of Younes Asakereh, the street vendor who set himself on fire to protest the failure of city officials to address his concerns about the confiscation of his business gear, there have been a number of protests in various Khuzestan cities.
The rights groups have called on Iranian officials to inform the families of detainees about the whereabouts of their relatives.