A suicide bomber riding a booby-trapped motorcycle blew himself up at the communist party headquarters in central Baghdad, killing 5 people and injuring 15 others.
"We don't know why this happened to us," said Mufid Jaziri, a member of the party's politburo.
"None of our comrades were hurt or killed, just innocents and passers-by."
Police station destroyed
In other violence, Iraqi insurgents destroyed a police station south of the capital in a sustained attack with mortars and a car bomb, the prime minister's office said.
The blast and a subsequent mortars and small arms fire killed three officers and wounded several more, including eight US soldiers on the site, according to the US military.
The station cost nearly half a million dollars and had been opened in a joint US-Iraqi ceremony just two weeks earlier.
Day of carnage
In the nearby town of Mahmudiya today, a pair of bombs exploded not far from an Iraqi army base, killing five civilians and wounding eight.
Another roadside bomb, this time in Latifiyah, another town in the violence-plagued area, went off next to a truck belonging to the finance ministry. One man was killed and five wounded.
In the central Baghdad neighbourhood of Zayuna a car bomb exploded, wounding three people and attracting a mix of police and bystanders who then fell prey to a second explosion.
Two civilians were killed in that blast and 23 others, including eight policemen, were wounded, medics said.
Clashes between armed groups in the south-west Baghdad neighbourhood of Amil resulted in three deaths and 10 wounded, according to police.
The area is a faultline between Sunni and Shi'ite neighbourhoods and often attacked by Shi'ite militias.
In Diyala province, a roadside bomb blew up an ambulance rushing to the hospital, killing the driver and the medic inside on the way to the provincial capital of Baquba.
In and around Baquba itself, another five people died in a series of attacks.
In the arid plains north of the capital, there were a number of attacks on the country's all important oil industry, including the murder of an engineer with the Northern Oil Company, outside his home in Samarra.
Farther north, the all important pipeline shipping crude oil from the fields around Kirkuk to the massive refinery in Baiji was blown up, apparently by mortar attacks.
Kirkuk itself was not spared. Three car bombs, including two practically at the same time, rocked the city, killing three civilians and wounding at least seven.
Seven bodies were also found by police in various places in the country, including those of a number of former members of the Baath party and a soldier.