Iraq's president has added his voice to those of thousands of street protesters on Saturday in denouncing US forces after they arrested the son of one of the country's top Shiite leaders.
President Jalal Talabani demanded "guarantees that such abuses will not be repeated" after the US military confirmed it had briefly held Ammar al-Hakim, the son of powerful Shiite politician Abdel Aziz-Hakim.
The political storm over the treatment of Hakim junior broke as his father's Baghdad house was targeted by a suicide bomber, who detonated his deadly load of explosives nearby after coming under fire from police.
"President Talabani expressed deep regret and sorrow over what happened to the well known national personality Sayyid Ammar al-Hakim," Talabani's office said in a statement, using the honorific for a descendant of the Prophet.
"President Talabani judges that the treatment of Sayyid al-Hakim was uncivilised and indecent, and he has demanded that the American leadership hold those behind it responsible," it said.
US officials insisted that Hakim was "treated with dignity" and had not been specifically targeted but rather detained after troops guarding the Iranian border deemed him to be acting suspiciously.
Hakim senior is the leader of the Supreme Council for the Islamic Revolution in Iraq (SCIRI), the second-strongest party in the Iraqi parliament, which was set up in 1982 by Iraqi exiles in Iran and which retains links to Tehran.
Hakim's son told a news conference in the Iraqi holy city of Najaf that he believed the US military had deliberately targeted him and accused the troops of treating him roughly after they picked him up on Friday.
"Senior officials planned to arrest me and these officials gave instructions to personnel at the site," he said. "They tied my hands and blindfolded me."
The US military confirmed that Hakim had been picked up at the Mehran border crossing, describing his detention as an "unfortunate incident."
"His convoy was initially stopped because the vehicles met specific criteria for further investigation in an area where smuggling activity has taken place in the past," US spokesman Lieutenant Colonel Chris Garver said.
"Mr Hakim was treated with dignity and respect throughout the incident."
Meanwhile, thousands of Iraqi Shiites took to the streets of central Iraqi cities to protest against Friday's incident.
"We would sacrifice our blood for you, Ammar," chanted a crowd in Kut, a Shiite town near the Mehran frontier post near where Hakim was detained.
In Najaf, a Shiite holy city in central Iraq, thousands of demonstrators poured through the old city near the sacred mausoleum of Imam Ali. Preachers demanded that the United States apologise for the arrest.
Iraqi and US forces are tightening security on Iraq's border with Iran, and Washington accuses Tehran of smuggling weapons into Iraq to arm the illegal Shiite militias fighting the US military.
"I express my regret for this arrest," US ambassador Zalmay Khalilzad said, in remarks translated into Arabic on Iraqi television.
"We don't mean any disrespect to Sayyid Abdel Aziz al-Hakim or his family."
Meanwhile, bomb and mortar attacks left 12 civilians dead in Baghdad and eight Iraqi police commandos were killed in an insurgent assault on an armed checkpoint near the city's airport.
An interior ministry official said three civilian bystanders were killed in the bomb attack near Hakim senior's house in the capital.
The official told AFP the attacker struck the first barrier protecting an access road leading from Al-Hussein Square in downtown Baghdad's Jadriyah district towards Hakim's fortified compound.
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He tried to break through the first barrier towards Hakim's house. The guards opened fire on him and he blew himself up, killing one of them and wounding four," said the official, speaking on condition of anonymity.
Also on Saturday, Iraqi troops backed by US aircraft killed "tens" of insurgents in a major assault on the hideout of the Islamic Army in Iraq, a Sunni militant group, a senior interior ministry official said.
