Baghdad (CNN) -- A spate of car bombings rocked Iraq on Tuesday, the ninth anniversary of the U.S. invasion and days before the nation hosts a meeting of Arab leaders.
The violence left at least 45 people dead and 216 wounded, officials said.
No one immediately claimed responsibility for the blasts that one senior Interior Ministry official described as "coordinated" and blamed on al Qaeda in Iraq.
The official, who did not want to be named because he's not authorized to speak to the media, said the attacks were meant to send a message that the militant group -- despite gains made by Iraqi security forces -- is still able to carry out daily attacks.
Attacks took place in Baghdad, Kirkuk, Karbala, Hilla, Tikrit, Baiji, Ramadi, Mosul, Falluja, Diyala province, Salaheddin province, Samarra and Mahmoudiya.
Some of them targeted police or government facilities.
In central Falluja, a pregnant woman was killed and her 6-year-old child wounded by bombs insurgents planted around a house belonging to a police officer, police in the city said.
In Tikrit, a car bombing outside a school wounded four teachers. The attack in Hilla targeted a juvenile detention center; two attacks in Karbala targeted police stations; an army convoy was attacked in Ramadi; and a parked car exploded in front of the Foreign Ministry in Baghdad, officials said.
The highest death tolls came from a series of car bomb attacks in Karbala where 13 people were killed.
The Minister of State, Government Spokesman Ali al-Dabbagh announced that the Council of Ministers has decided that Baghdad will observe a national holiday, Iraqiya State TV reported.
It will begin on Sunday, said state TV.
The violence is the worst since February 23, when 50 people were killed and more than 200 were wounded in a string of attacks.
Iraqi officials have expressed concern that the continuing violence could cast a shadow as the country prepares to host the next Arab League summit on March 29.
The attacks on Tuesday come nine years to the day since a U.S.-led army invaded Iraq on March 20, 2003, toppling longtime dictator Saddam Hussein.
The United States argued Hussein's regime had been harboring forbidden stockpiles of chemical and biological weapons, long-range missiles and a nuclear weapons program.
Inspectors later found that Baghdad had attempted to conceal some weapons-related research from the international community, but that Iraq had been effectively disarmed under U.N. sanctions in the 1990s.
The invasion swiftly toppled Hussein, who was later executed for the massacre of Shiite villagers following an assassination attempt in the 1980s.
But years of bloodshed followed the invasion as an insurgency led by Hussein's allies took root, followed by sectarian warfare between Iraq's Shiite majority and its Sunni minority.
Nearly 4,500 Americans and 300-plus allied troops were killed before the last American troops left in December, while estimates of the Iraqi toll run well above 100,000.