The US military said Iraqi and American troops were restoring order in the town of Balad and the killing fields around, a region convulsed by the random slaughter of civilians by rival Sunni and Shia death squads.
"The violence began when 19 Shia were kidnapped and killed Friday in Al-Dhuluiyah, east of Balad. The following day, more than 38 Sunnis were killed in retaliation," the US military said in a statement.
"Also, in the past 48 hours, the city has been hit with five indirect fire attacks, killing six civilians and wounding 10," it added, referring to mortar fire.
Malik Laftah, the head of Balad city council, told AFP many corpses were still lying in the streets and that 17 mortar shells had hit the city limits Tuesday, indicating the final toll could be higher.
"No one dares to move around and the Mehdi Army is controlling the town," he said, referring to the powerful militia loyal to the Shia cleric Moqtada al-Sadr, which has been accused of taking part in the attacks.
The coalition insisted, however, that US and Iraqi government forces were now in control, having decreed a vehicle curfew and set up checkpoints to prevent Shia and Sunni gangs from continuing the slaughter.
"We continue to conduct our normal patrols in the city and provide support for Iraqi security forces as they lead operations in stopping the sectarian violence in Balad," said US army Lieutenant Colonel Jeffery Martindale.
Martindale also, however, confirmed that two Iraqi police officers had been arrested for taking part in the massacre which triggered the orgy of violence.
Iraqi police are often accused of collaborating with illegal militia, and on Tuesday the interior ministry announced that it was to reorganise the force.
Ministry spokesman Brigadier General Abdul Karim Khalaf told reporters that 1,228 officers had been sacked for breaking the law while nearly 2,000 more were purged from the ranks for dereliction of duty.
"This restructuring was applied this week to the leadership of the National Police," Khalaf said. "The headquarters of two divisions were dissolved and all brigades were brought directly under the commander of the National Police."
The National Police was hastily thrown together to address security shortages and is notorious for being infiltrated by the very Shia militias which US commanders now say are the biggest threat to Iraq's stability.
"The government is determined to fight the armed groups by all political or military means," the office of Prime Minister Nuri al-Maliki said Tuesday.
"It will not hesitate to strike whoever tries to violate the security of the country and threaten the civil peace," the statement added.
Maliki's restatement of a long-standing promise came amid mounting concern among his backers in the United States that his government has failed to rise to the challenge posed by the militias and their political sponsors.
"There is more to be done," said White House spokesman Tony Snow on Monday.
"The violence level is absolutely unacceptable and it is important to make progress," he said while stressing, however, that President George W. Bush "believes the prime minister is doing everything in his power to do it".
The next challenge to Maliki's authority could come from Sadr's movement, which reacted with fury Tuesday to the arrest of one of its most important precinct captains, allegedly by US forces.
"US forces raided the home of Sheikh Mazen al-Saedi, head of the Sadr movement offices in Karkh (west Baghdad) and arrested him," Hamdallah al-Rikabi, a spokesman for Sadr's movement, told AFP.
"Five other members of the office were arrested as well in a series of raids in Shuala," he said, referring to a Shia neighbourhood in north-east Baghdad.
The coalition would not immediately comment on the claim.
"Sadr's office is preparing for an official massive demonstration tomorrow in Karkh in which schools and some government departments will be involved," Rikabi threatened.
In addition to fielding several thousand armed Mehdi Army militiamen, Sadr's movement also has 30 seats in parliament and controls three ministries.
Meanwhile, violence continued elsewhere in Iraq.
Insurgents detonated a suicide car bomb in the southern Baghdad suburb of Saidiyah, killing two National Police commandos and wounding nine people.
A mortar shell crashed into Wathiq Square in Baghdad's middle-class Karrada neighbourhood, killing three people including a policeman and wounding seven more, a security official said.
In the southern city of Basra, gynaecologist Dr Youssra Hashem became the latest female professional to be killed amid a rise in violence against women, health spokesman Kadhim Jawad said.
Four university students were also gunned down, Basra police said.

Copyright AFP (Agence France-Presse), 2006