Reporters Without Borders says neither Asefi's family nor his lawyers know where he is being held or what he is charged with.
The group says Asefi is the third journalist to be arrested in Iran in the past week. His detention brings to 11 the number of journalists and cyber-dissidents held in Iran.
Reporters Without Borders also condemns the suspension on August 6 of the leading reformist daily "Sharq," the second time in a year the newspaper has been banned.
RFE/RL Iran Report
SUBSCRIBE For regular news and analysis on Iran by e-mail, subscribe to "RFE/RL Iran Report."