Agence France Presse says Iran is holding one of its reporters who was covering mass demonstrations in Tehran this week.
The French news agency's acting Tehran bureau chief, Jay Deshmukh, says he has not heard from Farhad Pouladi since the reporter was taken into custody Wednesday.
AFP says Iranian security forces detained Pouladi as he was going to cover a government-sponsored rally marking the 30th anniversary of the seizure of the U.S. Embassy.
In another area of Tehran Wednesday, police chased and beat opposition activists protesting the government of President Mahmoud Ahmadinejad.
The International Campaign for Human Rights in Iran says security forces and militia used "brutal force" to disperse the thousands of Iranians who joined the protests in Tehran and other cities.
The group says the crackdown resulted in many injuries and arrests. Tehran has not commented on the report.
Iran has banned foreign journalists from covering street protests since massive demonstrations broke out in June following the disputed re-election of President Ahmadinejad.
Thousands of people and a number of journalists were arrested during those demonstrations.
Some information for this report was provided by AFP and Reuters.