In a daring daylight operation gunmen - some dressed in security uniforms - kidnapped Ammar al-Assafar, a Shia, from his home in Baghdad's Sunni district of Adhamiyah, a security source said.
"Gunmen came in four cars and kidnapped the minister from his home in Adhamiyah," the source said.
His was the most high profile abduction since Sunni MP Taisheer al-Mashhadani was kidnapped on July 1, allegedly by Shia militiamen. She was abducted along with her seven bodyguards but was later released.
Assafar's seizure also comes after the kidnapping of five Westerners in southern Iraq on Thursday and the mass abduction of dozens of men from a Baghdad ministry building last week.
The day's most brutal attack came when a suicide car bomber posing as a contractor looking for workers blew himself up among a crowd of labourers in the mainly Shiite town of Hilla south of the capital, killing at least 22 people and wounding 44, police said.
"He came to the area asking for labourers and as these dozens of workers gathered around his car, he blew himself up," witness Haider Ali, 25, told AFP.
Minutes before Syria's Muallem addressed reporters in Baghdad, state-run television Al-Iraqiya announced that the suicide car bomber was "a Syrian."
It said two Egyptians and one Iraqi were also arrested for the bombing.
Eight were killed and two more wounded when gunmen sprayed their minibus with bullets, police said. In the northern oil town of Kirkuk on Sunday, the Iraqi army said it had killed eight members of al Qaeda in Iraq and wounded 11 more.