A car bomb slaughtered 47 people in Iraq's pilgrimage city of Karbala on Saturday, the latest brazen attack to undermine a security crackdown exactly two months after it began in Baghdad.
In the capital, 10 people died in a suicide attack while other attacks around the country killed another nine people, pushing the death toll to 66 before lunchtime.
The latest carnage comes two days after a suicide bombing in parliament's cafe stunned the world for its massive breach of security.
The Karbala bomb exploded in an area cluttered with popular market stalls around 200 metres from the Imam Hussein shrine, where hundreds of thousands of Shiite pilgrims flock every March during the Ashura commemorations.
At least 47 people were killed and another 62 wounded, said an Iraqi army source. Local security spokesman Rahman Mushawi earlier confirmed 40 people killed in the blast outside a bus station, car park and market stall complex.
Debris from smashed stalls was strewn on the ground as civilians helped ferry the wounded into ambulances.
Shocked and dazed men wiped tears from their eyes, turning away from the bombing site engulfed in thick grey smoke.
Women and children were among the casualties, and four Iranians were counted among the wounded at hospital on the second day of the Iraqi weekend.
In Baghdad, a suicide bomber detonated his car next to a security checkpoint at the edge of the Jadiriyah bridge, killing 10 people and leaving another 15 wounded, most of them civilians, a security official said.
Shortly after daybreak, gunmen attacked the home of top Sunni politician Adnan al-Dulaimi and clashed with guards in a shootout that left five of the MP's security retinue wounded, a member of Dulaimi's political party said.
Saturday's violence was the latest defiance of a massive security crackdown launched exactly two months ago in Baghdad, where about 80,000 Iraqi and US troops are patrolling the capital, and since extended to other cities.
Although Iraqi and US officials say the crackdown has seen a fall in execution-style killings in the capital, they admit bombings remain a curse and that militants have increasingly taken the fight outside Baghdad.
Nassar al-Rubaie, a member of the political grouping of radical Shiite cleric Moqtada al-Sadr bitterly opposed to the ongoing US-led foreign presence in Iraq, slammed the crackdown for failing to stop mass car bombings. "On the ground bombings are still continuing... Has the Mahdi Army ever been accused of these bombings? No. There should be pressure on those carrying out such bombings due to the wide dissemination of security troops," he said.
The US military announced the deaths of three American soldiers killed south of Baghdad on Friday, two of whom died with two Iraqi interpreters when their patrol base was ambushed in an attack that saw combat helicopters scrambled.
The helicopters and a quick reaction force raced to the scene to repel the attack, which left another seven US troops wounded, the army said.
The latest fatalities brought the US military's losses in Iraq to 3,293 since the March 2003 invasion, according to an agency count based on Pentagon figures, a body count upping domestic American calls for troops to withdraw.
On a visit to Washington, government spokesman Ali al-Dabbagh warned that a premature US troop withdrawal would lead to a power vacuum in Iraq.
Thursday's parliament attack, in which one lawmaker was killed, also forced the second-ranking US general in Iraq, General Raymond Odierno, to admit there was still a "long way to go" towards providing security.
At an extraordinary session convened on the Muslim day of rest on Friday, Iraqi lawmakers condemned the suicide attack in their canteen and vowed to press forward with the political process in a call for unity against extremism.
An alliance of Sunni insurgent groups that includes Al-Qaeda in Iraq claimed responsibility for the attack on the Internet.