The body of the nephew of Iran's opposition leader — killed in the deadliest day of anti-government protests in months — disappeared from a hospital Monday, and security forces detained at least seven prominent activists, opposition reports said.

Iranian state television reported that eight people had died in the street violence Sunday, but independent confirmation of the casualty toll was virtually impossible because of curbs on media coverage. Tehran residents say restrictions on Internet access were intensified, and Iranians were unable to see opposition Web sites. Cell phone and text messaging services were sporadic.

Reza Mousavi said Monday that the body of his brother, Ali Mousavi, was taken overnight from a Tehran hospital and that nobody had accepted "responsibility" for removing the corpse. Authorities were possibly seeking to deter mourners from organizing more protests around the funeral.

The slain man was the nephew of opposition leader Mir Hossein Mousavi, a presidential contender in a disputed election in June.

The bloodshed Sunday drew harsh condemnation from one opposition leader, who compared the government to the dictatorship that was ousted by the Islamic Revolution three decades ago.

Mahdi Karroubi, an opposition leader who ran in the June election, posted a statement on an opposition Web site asking how the government could spill the blood of its people during commemorations of Shiite Islam's most important observance, Ashoura.

He told the Rah-e-Sabz Web site that even the former government of the hated shah, who was overthrown in 1979, respected the holy day, and described those who confronted the protesters as "savage individuals."

Comparing a rival to the shah is a serious, though common, insult in Iranian politics.

The government crackdown drew sharp criticism from the West, which is already locked in a dispute with Iran over its suspected efforts to develop nuclear weapons. Iran says its nuclear program is for peaceful purposes.

Germany's foreign minister, Guido Westerwelle, condemned the "brutal action" by security forces.

"I am calling on those responsible in Tehran to do everything in order to avoid a further escalation of the situation and to end the violence," he said. "The international community will watch and not look away."

Foreign Secretary David Miliband of Britain said it was "particularly disturbing" to hear reports of the crackdown by security forces on the sacred occasion of Ashoura, and urged Iran to respect human rights.

The French Foreign Ministry reiterated its "great anxiety" over the situation in Iran and again condemned "arbitrary arrests and violence against simple demonstrators."

Also Monday, a Dubai television company says it hasn't heard from its correspondent in Iran since he went missing near his house in Tehran on Sunday afternoon.

Dubai Media Incorporated said it was in touch with Iranian officials about the fate of Reza al-Basha, a 27-year-old Syrian. Dubai Media is the government-owned parent of a handful of television stations in the emirate.

Sunday's violence erupted when security forces fired on stone-throwing protesters in the center of Tehran. Opposition Web sites and witnesses said five people were killed, but Iran's state-run Press TV, quoting the Supreme National Security Council, said the death toll was eight.

Opposition Web sites and activists said security forces raided a series of opposition offices on Monday, making at least seven arrests.

The Parlemannews site said three of Moussavi's top aides were rounded up, including his top adviser, Ali Riza Beheshti.

Security forces also stormed a foundation run by reformist former President Mohammad Khatami and arrested two people, a foundation official said, speaking on condition of anonymity because of fears of police reprisal. The Baran Foundation works to promote dialogue between civilizations.

Also, former Foreign Minister Ebrahim Yazdi and human rights activist Emad Baghi were arrested, according to the Rah-e-Sabz Web site. Yazdi, who served as foreign minister after the 1979 Islamic revolution, is now leader of the banned but tolerated Freedom Movement of Iran.

The arrests could not be independently confirmed.

Police said dozens of officers were injured and more than 300 protesters were arrested in the violence Sunday.

The clashes marked the bloodiest confrontation since the height of unrest in the weeks after June's election. The opposition says Ahmadinejad won the election through massive vote fraud and that Mousavi was the true winner.

The Dec. 20 death of the 87-year-old Grand Ayatollah Hossein Ali Montazeri, a sharp critic of Iran's leaders, gave a new push to opposition protests. Opposition leaders have used holidays and other symbolic days in recent months to stage anti-government rallies.