ISTANBUL | The Iranian regime, desperate to restore order after massive protests, arrested more than 1,000 people Monday in an increasingly doubtful bid to suppress an opposition movement that appears to be growing stronger by the day.
Among those arrested were a septuagenarian former foreign minister and top aides to defeated presidential candidate Mir Hossein Mousavi and to former President Mohammed Khatami.
"They are arresting everybody," said Mehdi Noorbakhsh, an associate professor of international affairs at Pennsylvania's Harrisburg University. "They're trying to ban political parties, gatherings, everything."
Journalists, human rights and women's activists, and relatives of some of those who died in Sunday's clashes were also among those detained.
One high-profile detainee was Ebrahim Yazdi, 78, the Islamic republic's first foreign minister and currently the head of the liberal Freedom Movement.
"They arrested Mr. Yazdi at 3 a.m. alongside his 25-year-old niece who is a politically active student," said Mr. Noorbakhsh, who is Mr. Yazdi's son-in-law. "They arrested him because they believe that this way they'll stop the younger generation from taking to the streets."
Iran analysts said that the chances of that happening were slim and that the arrests reflected the regime's desperation.
"We shouldn't think that this government is behaving in a rational way," said Mehdi Khalaji, an Iran analyst at the Washington Institute for Near East Policy.
Mr. Khalaji said the supreme leader, Ayatollah Ali Khamenei, had needlessly antagonized new constituencies within Iran by, for example, forbidding proper mourning ceremonies for a prominent dissident cleric, Grand Ayatollah Ali Montazeri, who died Dec. 20.
That behavior, he said, for the first time galvanized religious Iranians and clerics in the theological center of Qom, which remained relatively quiet after the June presidential election, which delivered a fraud-tainted victory to incumbent Mahmoud Ahmadinejad.
Mr. Khalaji noted, however, that Ayatollah Khamenei has not authorized the arrest of Mr. Mousavi; another presidential candidate, Mehdi Karroubi; or former Presidents Khatami and Akbar Hashemi Rafsanjani.
According to official media, at least eight people died in protests across the nation Sunday, the bloodiest day since June 20, when at least 11 people were killed.
President Obama issued unusually harsh criticism of the Iranian government Monday, saying that the U.S. "joins with the international community in strongly condemning the violent and unjust suppression of innocent Iranian citizens."
Tehran on Monday was largely "silent in a very strange way," said an Iranian in the capital who asked not to be named to protect himself from arrest. "There was no traffic in most crowded places. We all felt [like] the day after the election. People were shocked. I haven't heard nor seen any protests or militia anywhere today. Anti-riot [police] stayed in a few famous squares and there were clashes in Hafteh Tir Square."
The Revolutionary Guard-owned Fars news agency reported a pro-regime demonstration in Qom and condemnations by a stream of conservative religious figures over what they described as the "disrespect to Ashura."
Ashura, which for many Shi'ites fell this year on Sunday, is the most emotional day of the year for Shi'ite Muslims and commemorates the day in 680 when the prophet Muhammad's grandson, Hossein, died near Karbala in a battle with the forces of a tyrant, Yazid.
Protesters on Sunday compared Ayatollah Khamenei to Yazid, a massive insult. Demonstrators also fought police and paramilitary Basij members with stones and the police's own batons. Mr. Khalaji said some of the casualties may have been caused by security forces acting in self-defense.
The official Islamic Republic News Agency reported Monday that 47 student unions across the country had demanded that the government deal harshly with the protesters. The report could not be independently confirmed and seemed to contradict indications that Iranian students largely support the protests.
The pro-government Raja News Agency also reported the arrest of a British passport holder accused of "attacked mourners" in a central Tehran crossroads. The news agency said the person was carrying his British passport at the time of arrest but did not give a name.
Also Monday, Persian-language media reported the arrest of a Syrian journalist who was observing protests close to his house in Iran. A Dubai-based television company announced that it had not heard from correspondent Reza al-Basha since Sunday afternoon. Parent company Dubai Media Inc. said it was in touch with Iranian officials.
Reports conflicted about the cause of death Sunday of Mr. Mousavi's nephew, Ali. Mohsen Makhmalbaf, a prominent filmmaker and spokesman for the Iranian opposition based in Paris, said the younger Mr. Mousavi was run over outside his home by security men in a sport utility vehicle and then shot. Other reports on opposition Web sites said the man was killed by a sniper during demonstrations.
Iranian reporters and foreign correspondents have been barred from covering the demonstrations, making it impossible to independently verify these accounts.
Iranian state media said authorities had taken the bodies of five people killed Sunday for forensic tests, violating a religious tenet that the dead should be buried swiftly. Relatives of the slain Ali Mousavi said they could not find his body for burial, opposition Web sites said.
Human Rights and Democracy Activists in Iran reported abuses of patients. The organization quoted hospital sources claiming that Intelligence Ministry officials "interrogated and recorded the personal details of the wounded being transferred to hospitals after they arrived with the assistance of medical staff."
During the summer, many protesters wounded in the riots refused to be treated in hospitals out of fear that they would be arrested. In one case, dissidents set up an underground network of trusted doctors who would visit patients in their homes.
Some of the most violent protests Sunday occurred in Tehran's traditional Imam Hossein district and the tony northern suburbs of Tehran, pointing to an emerging alliance of rich and poor.
"Those living in Imam Hossein are a mixture of Tehran's original inhabitants and small-time shop owners which Ahmadinejad claims are his supporters," said Delbar Tavakoli, a journalist for the closed reformist newspaper Etemad who is in exile in Turkey. "When these two social extremes come together, this movement has broken down social class. Everyone is out protesting."
Mr. Khalaji predicted more bloodshed as the government tries with greater difficulty to stifle the opposition.
"This government will be more aggressive," he said. "We are expecting more violent scenes in coming days."
• Barbara Slavin reported from Washington.