TEHRAN, Iran — Iranian security forces stormed opposition offices in a series of raids Monday and rounded up at least a dozen prominent dissidents in a new crackdown on the country's reformist movement, opposition Web sites and activists reported.
The arrests came a day after violent clashes between antigovernment demonstrators and security forces coinciding with Ashoura, the peak of an intense mourning period in Shiite Islam. At least eight people were killed, state television reported.
Among those reported arrested were Ali Reza Beheshti, a top aide to political opposition leader Mir Hossein Mousavi; Emadeddin Baghi, a human rights activist; and Ibrahim Yazdi, a 78-year-old former foreign minister who was in Iran's first government after the 1979 Islamic revolution.
More than 300 protesters were arrested Sunday during violence that left dozens of officers injured, police said. Video posted on the Internet showed wounded protesters, their heads bloodied in clashes with club-wielding security forces.
President Barack Obama expressed solidarity with opponents of Iranian President Mahmoud Ahmadinejad and called for the immediate release of those "unjustly detained" in Iran.
European leaders joined in condemning the crackdown. German Chancellor Angela Merkel urged Iran to respect "the right to free speech through peaceful demonstrations."
Mehdi Karroubi, an opposition leader who ran in Iran's June 12 presidential election, posted a statement on an opposition Web site asking how the government could shed its people's blood on the Shiite sacred day of Ashoura and denouncing the perpetrators as "a group of savage individuals." He said even the former government of the shah of Iran respected the holy day.
Relatives and opposition Web sites charged that the body of a slain opposition figure had disappeared from a local hospital, forcing the cancellation of a memorial service at which protesters had planned to gather. Ali Mousavi, a nephew of Mir Hossein Mousavi, was apparently gunned down in a Tehran street during Sunday's clashes.
The official Islamic Republic News Agency denied that the body was missing and said it was being held for "further investigation."