Earlier on Wednesday, three car bombs exploded across the capital.
One car bomb targeted a transit area near a busy market in central Baghdad where people wait to catch minibuses. Four people were killed and 12 were wounded, police said.
Another car packed with explosives blew up in the religiously mixed neighbourhood of Maamoun in western Baghdad at about the same time, killing two civilians and wounding three others, police said.
The third car bomb exploded outside a currency exchange in a mainly Shia area of eastern Baghdad, killing two people and wounding 10, police said.
"A seemingly normal person parked this car and told us that he would not be long," the owner told the Associated Press. "When that person disappeared for more than 20 minutes, we tried to call the police but the car exploded as we were trying to do so."
Shop owners often insist that motorists get permission before parking their cars due to the frequent car bombings in the capital.
Iraqi authorities have promised to crack down on Sunni fighters and Shia militia when a joint neighbourhood-by-neighbourhood sweep of Baghdad is carried out with the US military.
US military deaths
The US military also announced that four soldiers had been killed during two separate incidents in western Iraq, taking the total to 3,079 since March 2003.
|Nine mortar shells hit a mainly Sunni |
neighbourhood of Baghdad [AFP]
Across Iraq, at least 47 people were killed in continuing violence.
Iraq has meanwhile invited neighbouring countries, including Iran, to Baghdad in March to discuss ways of increasing security in the country, a senior official said.
A foreign ministry official said invitations had been sent to neighbouring Iran, Jordan, Kuwait, Saudi Arabia, Syria and Turkey as well as Egypt, Bahrain, the Arab League and the Organisation of the Islamic Conference.
Iraq's neighbours fear that the sectarian conflict will spill over into the region.
The United States, which has steadfastly refused to engage directly with Iran or Syria in its efforts to help stabilise Iraq, welcomed the proposed confernce.
"Certainly we would have a positive view of the Iraqis holding such a regional conference," Sean McCormack, the US state department spokesman, said.
Iran and Syria, both accused by the United States of supporting elements carrying out the violence in Iraq, jointly called for such a regional conference in January.