An Islamic State car bomb has killed 24 people in a busy square in Baghdad's sprawling Sadr City district.
The militants also cut a key road north from the capital to Mosul, their last major stronghold in the country.
An online statement distributed by Amaq news agency, which supports Islamic State, said the group had targeted a gathering of Shi'ite Muslims. Sixty-seven people were wounded in the blast.
Monday's blast in Sadr City hit a square where day labourers typically gather.
Nine of the victims were women in a passing minibus. Their charred bodies were visible inside the burnt-out remains of the vehicle. Blood stained the ground nearby.
"The terrorists will attempt to attack civilians in order to make up for their losses, but we assure the Iraqi people and the world that we are able to end terrorism and shorten its life," Prime Minister Haider al-Abadi said after a meeting with the visiting French president, Francois Hollande.
Meanwhile, as clashes continued in and around Mosul on Monday, Islamic State also targeted military positions away from the main battlefield, killing at least 16 pro-government fighters and cutting a strategic road linking the city to Baghdad.
Militants attacked an army barracks near Baiji, 180 km north of the capital, killing four soldiers and wounding 12 people, army and police sources said.
They seized weapons there and launched mortars at nearby Shirqat, forcing security forces to impose a curfew and close schools and offices in the town, according to local officials and security sources.
Shirqat mayor Ali Dodah said Islamic State seized three checkpoints on the main road linking Baiji to Shirqat following the attacks.
In a separate incident, gunmen broke into a village near Udhaim, 90 km north of Baghdad, where they executed nine Sunni tribal fighters with shots to the head, police and medical sources said.
At least three pro-government Shi'ite militia fighters were also killed and seven wounded when militants attacked their position near Udhaim with mortar rounds and machine guns, police sources said.
