Police sources said three of the industry minister's bodyguards were killed in the blasts, but Fawzi al-Hariri was not with the convoy at the time.
"The minister is at the ministry and perfectly safe," a spokesman for al-Hariri said.
Drivers and bodyguards for one of al-Hariri's deputies had been taking the cars for fuel when the attack happened.
A bomb detonated in the Karrada district of the mainly Christian Camp Sara neighbourhood as the convoy passed, police said. Subsequent explosions outside a nearby market also caused casualties.
At least 75 people have been injured, police said.
Corpses were seen lying in the streets as people ferried the wounded to hospital in private cars before ambulances arrived.
Two buildings were severely damaged and dozens of shops destroyed.
Another car bomb in the capital's Dura district also killed one person on Wednesday.
In Ramadi, a suspected truck bomb exploded outside the Iraqi army headquarters but caused no casualties, police said. Guards opened fire on the vehicle as it drove towards a checkpoint and it crashed into concrete blocks and exploded.
Iraqi authorities have taken a police brigade out of service and returned them to training because of "complicity" with death squads in Baghdad, a US military spokesman said.
The police officers have been told to stand down after armed men stormed into a frozen meats factory in the Amil district and snatched 24 workers on Sunday. The bodies of seven of the workers were found later but the fate of the others remains unknown.
Sunni leaders blamed Shia militias and suggested security forces had turned a blind eye to the attack.
"There was some possible complicity in allowing death squad elements to move freely when they should have been impeding them."
Major-General William Caldwell, US military spokesman in Iraq
Major-General William Caldwell, US military spokesman in Iraq, said: "There was some possible complicity in allowing death squad elements to move freely when they should have been impeding them.
"The forces in the unit have not put their full allegiance to the government of Iraq and gave their allegiance to others," he said.
The Iraqi interior ministry said on Tuesday that the commander of the unit, a lieutenant colonel, had been detained and was being investigated. The major general who commands the battalion that includes the suspended brigade has been suspended temporarily and his transfer ordered.
In the Diyala province, more than 250 people have been arrested on suspicion of belonging to armed groups and militias, an Iraqi army source said.
Large amounts of weapons and ammunition have been found during the raids, the source said.
The US military also announced that two soldiers had died on Tuesday. One was killed near the northern Iraqi city of Kirkuk and the other in eastern Baghdad.