The official, speaking on condition of anonymity, said two Iraqis and two Saudis were grabbed shortly after the Friday bombing, admitted al Qaeda ties and gave information leading to the arrest of the 15 others. They include two Kuwaitis and six Palestinians with Jordanian passports. The remainder were Iraqis and Saudis the official said, without giving a breakdown.
"Initial information shows they (the foreigners) entered the country from Kuwait, Syria and Jordan," the official said. "All those arrested belong to the Wahhabi sect (of Sunni Islam), and they are all connected to al Qaeda," the official said.
Wahhabism is the strict, fundamentalist branch of Sunni Islam from which Osama bin Laden, the al Qaeda leader, draws spiritual direction. Based in Saudi Arabia, its followers show little tolerance for non-Wahhabi Sunnis and Shiites. Bin Laden was born in Saudi Arabia, where Wahhabism originated in the 18th century.
U.S. officials have not confirmed any of the details of the arrests, and have not taken an active role in the investigation because of Iraqi sensitivity to any U.S. presence at the holy site.
But the arrests would seem to substantiate Bush administration claims that bin Laden's followers have taken their Islamic militant war against the West to Iraq, where U.S. forces are struggling to maintain security.
Hospital officials said 85 people died, including leading Shiite Muslim cleric Ayatollah Mohammed Baqir al-Hakim. Earlier counts had put the toll higher, but were reduced after some deaths were found to have been reported twice.
Thousands of angry mourners called for vengeance as they gathered outside the Imam Ali shrine on Saturday.
In other developments:
Tens of thousands of worshippers filled the shrine in Najaf and the surrounding streets for a funeral service for the victims. There was to be a service for al-Hakim in Baghdad early Sunday with the body then taken to Karbala, near Najaf. It was to be buried in Najaf on Tuesday.
In Najaf, the main road leading to the shrine was open only to pedestrians, and residents were seen carrying coffins on the tops of cars and backs of trucks for the funeral service.
CBS News Reporter Lisa Barron says the Najaf demonstration turned into an angry anti-American protest, with al Hakim's nephew telling the crowd the U.S.-led coalition isn't welcome in Iraq and should hand over security to Iraqis. He said, "We will keep on working until we raise the flag of Islam on the lands of the Mesopotamia." Barron says the demonstrators yelled, "Death to America."
In Baghdad, about 3,000 Shiites protested peacefully for about an hour at the gates of coalition headquarters, complaining that the coalition's failure to provide security led to al-Hakim's death. Barron, who is in Baghdad, said the crowd chanted anti-American and anti-Baath Party slogans, such as, "No to America, no to Saddam, yes to Islam."
The AP's Najaf police source, who led the initial investigation and interrogation of the captives, said the prisoners told of other plots to kill political and religious leaders and to damage vital installations such as power plants, water supplies and oil pipelines.
He said the men arrested after the attack claimed the recent bombings were designed to "keep Iraq in a state of chaos so that police and American forces are unable to focus attention" on the country's porous borders, across which suspected foreign fighters are said to be infiltrating.
The four men arrived in Najaf three days before the Friday bombing and were staying with a friend, who did not know their intentions, the official said.
Early Saturday, a fresh explosion and fire hit the export pipeline carrying oil from Iraq's northern Kirkuk fields to Turkey. The huge blaze burned out of control further delaying the resumption of the vital link which is costing Iraqis an estimated $7 million a day it is out of operation. The explosion and fire were the fourth to hit the line since it briefly reopened earlier this month.
Police pointed to similarities between the mosque bombing and two recent attacks.
The Najaf police official said the bomb at the Imam Ali shrine - the burial place of the son-in-law of the Prophet Muhammad - was made from the same type of materials used in the Aug. 19 bombing at the U.N. headquarters in Baghdad, in which at least 23 people died, and the Jordanian Embassy attack on Aug. 7. Nineteen people died in that vehicle bombing.
The FBI said the U.N. bomb was constructed from ordnance left over from the regime of Saddam Hussein, with much of it produced in the former Soviet Union. In the truck bomb used against the world body, there were many explosives wired together, including a 500-pound Soviet-era bomb, the FBI said.
The Dubai-based Al-Arabiya satellite broadcast channel, quoting the Najaf governor, said 1,550 pounds of explosives were planted in two cars. The U.N. bomb was about 1,000 pounds.
A highly respected Shiite cleric suspended his membership in the U.S.-picked Iraqi interim Governing Council on Saturday, citing a lack of security after Najaf bombing.
Mohammed Bahr al-Uloum, who came back from exile in London after the fall of Saddam Hussein, said his return to the council depended on the U.S.-led coalition turning over security matters to Iraqis, so that Muslim shrines in the country could be under Islamic protection.
"This act has pushed me to postpone my membership in the governing council because it can't do anything concerning the security situation," he said.
The bombing investigation was being handled entirely by Iraqi police in Najaf, but the FBI would assist if asked, coalition spokesman Charles Heatley told reporters.
"It's clearly in our interests that those responsible be brought to justice," he said.
He said the coalition had sent $200,000 to Iraqi authorities in Najaf to be used for disaster relief and had earmarked $2 million for reconstruction in the city.
The coalition "roundly rejects" claims that it is not providing adequate security in Iraq, Heatley said.