A wave of car bombings and suicide attacks against Shi'ite Muslims ripped through Iraqi cities Monday, killing at least 76 people and wounding scores more, extending the worst sectarian violence since U.S. troops withdrew from the country in December 2011.
The attacks increased the number of Iraqis killed in sectarian clashes over the past week to more than 200, including 70 who died Friday in a series of bombings targeting Sunnis.
Monday's violence was extensive in Baghdad, where at least nine car bombs ripped through busy market places, crowded bus stops and other areas of Shi'ite neighborhoods, killing at least 25 and wounding 150.
Officials say two other car bombs killed 15 people in Basra, a predominantly Shi'ite city 420 kilometers south of Baghdad. In Balad, north of the capital, a car bomb targeted a bus of Iranian pilgrims, killing 12 Iranians and two Iraqis.
Two Shi'ite mosques were also bombed.
In the United States, White House spokesman Jay Carney condemned all the attacks in Iraq over the past several days, saying U.S. officials have been in contact with "a wide range of Iraqi leaders ... to help resolve ongoing political and sectarian tensions."
There was no immediate claim of responsibility for Monday's attacks, but the fact that they all occurred in Shi'ite areas raised the suspicion that Sunni militants were involved.
For months, Iraq's Sunnis have been protesting against Prime Minister Nouri al-Maliki, accusing his Shi'ite-led government of ignoring their needs and targeting them for arrest.
The unrest has raised fears of a return to the level of sectarian fighting that left tens of thousands dead in 2006 and 2007.
Violence has fallen from that peak, but the United Nations said 712 people were killed in April, making it the deadliest month in Iraq since June 2008.