Khazali is being held on charges of “acting against national security and disturbing public opinion” after being interrogated at the capital’s notorious Evin prison, the opposition website Rahesabz reported late on Wednesday.
A medical doctor and veteran of the 1980-88 war with Iraq, Khazali is the son of Ayatollah Abolqasem Khazali, a long-serving member of the Assembly of Experts, the clerical body which oversees the work of supreme leader Ayatollah Ali Khamenei.
Khazali has frequently poked fun at Ahmadinejad and his allies on his widely read blog, criticism which he intensified after his disqualification from standing as a candidate in parliamentary elections in 2008.
His father has disavowed his negative commentaries.
Khazali was also arrested last year as part of the government’s crackdown on the wave of mass street protests that greeted official results giving Ahamdinejad victory in a June presidential election. He was later released on bail.
Khazali was among scores of reformist politicians, journalists, human rights campaigners and student activists detained in the crackdown.
