The American military said those detained included alleged members of car bomb cells, financial networks and a suspect who allegedly assisted in the movement of suicide bombers from Iran to Iraq.

Most of the suspects were detained in Baghdad and the northern cities of Mosul and Kirkuk, which remain volatile despite improvements in security in many parts of the country.

The US military believes Al Qaeda in Iraq has received financial aid and weapons from sources in Iran.

US officials have accused Teheran of supporting militias in Iraq as part of its power struggle with the United States for influence in the Middle East, though militia activity has dropped sharply in Iraq.

Some observers believe there have been links between Iran and Sunni extremists seeking a common goal of undermining the United States despite their traditional animosity.

“Coalition forces will continue to target the Al Qaeda network to further diminish its ability to conduct terrorist attacks against the Iraqi people,” said Major John C. Hall, a US military spokesman.

The  suicide attack occurred in Kirkuk, a northern city with a volatile population of Kurds, Arabs and Turkomen whose disputed status has prevented parliament from passing a provincial election law that is key to reconciliation in Iraq.

Kurds want Kirkuk incorporated into their self-ruled northern region, but Arabs and Turkomen want it to stay under central government control.

South of Baghdad, officials in Najaf stepped up security measures ahead of Monday’s anniversary of the death of Imam Ali. About 15,000 Iraqi policemen and soldiers were deploying in and around the city to protect hundreds of thousands of pilgrims, said Colonel Ali Nomas, the Iraqi army spokesman. Insurgents have targeted pilgrims in the past. —