The deaths followed a day of bombings and shootings on Sunday, when more than 60 people were killed across the country, from the northern city of Kirkuk to the capital Baghdad and down to the south in Basra.
The dead included eight American soldiers, one of the deadliest weekends for the U.S. military in recent months.
In the city of Diwaniyah, gun battles between Iraqi forces and militiamen of the Mahdi Army loyal to radical cleric Muqtada al-Sadr left at least 34 people dead and about 70 wounded, Iraqi officials said.
The fighting broke out late Sunday night when Iraqi soldiers conducted raids in three neighborhoods to flush out the militiamen and seize weapons, said army Capt. Fatik Aied.
He said the fighting continued Monday.
In other developments:
Dr. Mohammed Abdul-Muhsen of the city's general hospital said 34 bodies were brought in — 25 Iraqi soldiers, seven civilians and two militiamen. He said at least 70 people were injured, but could not immediately give a breakdown.
Fatik said the militiamen were using rocket-propelled grenades and automatic assault rifles. At least 10 militiamen had been arrested, he said.
Diwaniyah, 80 miles south of Baghdad, is a Shiite-dominated city where the influence of Mahdi Army has been gradually increasing. It already runs a virtual parallel government in Sadr City, a slum in eastern Baghdad.
But the government of Prime Minister Nouri al-Maliki, a Shiite, has found it difficult to rein in al-Sadr, whose movement holds 30 of the 275 seats in parliament and five Cabinet posts.
Al-Sadr's backing also helped al-Maliki win the top job during painstaking negotiations within the Shiite alliance that led to the ouster of Prime Minister Ibrahim al-Jaafari.