Reports from Iran say authorities have detained the sister of Nobel peace laureate Shirin Ebadi.
A statement from Ebadi carried on an opposition website said Nushin Ebadi, a lecturer, was detained on December 28 at her home.
Shirin Ebadi told CNN her sister was not involved in human rights work and had not participated in any of the protests that followed June's disputed presidential election.
A prominent journalist, Mashallah Shamsolvaezin, and a women's rights activist, Mansoureh Shojaee, were also reportedly detained overnight.
The developments come after at least eight people were killed in clashes between opposition protesters and security forces on December 27, the worst unrest in months.
U.S. President Barack Obama on December 28 condemned the Iranian government's violent crackdown, referring to the bloodshed and arrests as an "iron fist of brutality."