Officials say that at least 15 people were killed and dozens of others injured in one attack today in the town of Mahmudiyah, south of the capital.
Reuters quoted the mayor of Mahmudiyah, Muaid al-Amiri, as saying a car bomb had exploded at industrial workshops, demolishing the multistory building.
Four others died in a car-bomb attack in Baghdad.
And an Iraqi policeman was killed when a roadside bomb targeted his patrol in Adhamiyah.
The U.S. military also announced the deaths of four U.S. soldiers, killed northeast of Baghdad on April 7.
The Iraqi government recently announced its extension of a joint U.S.-Iraqi security offensive that began in the capital in February to other cities.
Al-Sadr Calls For End To Cooperation With U.S.
Shi'ite cleric Muqtada al-Sadr has urged Iraqi forces to stop cooperating with the United States and instructed his followers to concentrate attacks on U.S. troops rather than Iraqis.
The call came in a statement distributed in the city of Al-Najaf today, one day ahead of a protest there to mark the fourth anniversary of the capture of Baghdad by U.S.-led forces.
The authenticity of the statement could not be verified, although at least one agency said it bore the stamp of al-Sadr's office.
Al-Sadr led two bloody campaigns against international forces before publicly joining the political process, but he still leads a network of armed fighters.
Baghdad Closed To Vehicles
Iraqi state television reported today that the Iraqi military has ordered a 24-hour vehicle ban in the capital on April 9, the fourth anniversary of Baghdad's fall to U.S.-led troops.
The ban also includes motorcycles.
Such bans in the past have been imposed to prevent vehicle bombings.
(compiled from agency reports)