Most attribute the violence to al-Qaida-affiliated insurgents emboldened by political feuding that has paralyzed the government and hoping to reignite fighting among the country's ethnic and sectarian factions.

More significant than the numbers was the fact that insurgents appeared able to sustain the level of violence over a longer period than before. There was a major bombing or shooting rampage almost every three days in June, many targeting Shiite pilgrims on their way to the annual Baghdad commemoration of a revered imam.

Another Shiite pilgrimage set for this week has security forces on high alert.

Hundreds of thousands of pilgrims are expected to travel to the holy city of Karbala, 80 kilometers (50 miles) south of Baghdad, for the festival of Shabaniyah, celebrating the birth of the ninth-century Shiite leader known as the Hidden Imam. The pilgrimage peaks on Friday.