The northern city of Mosul shuddered under 10 apparently co-ordinated attacks erupting at 20-minute intervals, including several suicide car bombs, mortar fire and small arms assaults against US-led forces and Iraqi police.
The bloodiest attack was a massive suicide truck bomb against a police station that local authorities say killed 11 and wounded 26 -- the vast majority of them innocent bystanders -- but more blasts followed.
Police have closed the entrances to the city and imposed a curfew following the 10 attacks, which took place over just three hours. The toll apart from the truck bomb was estimated at four civilian dead.
Two of the suicide attacks were against US forces, but there was no immediate word on military casualties.
Further south in the oil city of Kirkuk two suicide attacks a total of 18 people, while in the market town of Khalis in Diyala province a bomb in a crowded market killed 17 shoppers, police and medics said.
According to US military spokesman Major General Caldwell, the past three weeks have seen a shift in focus of attacks from civilians to both US and Iraqi security forces.
So far in October, he added, 73 US soldiers have been killed. US forces now lose an average of four soldiers a day and are thus on course to lose more in October than in any month since the battle of Fallujah in November 2004.
"The violence is indeed disheartening," Caldwell said. "In Baghdad alone we have seen a 22 percent increase in attacks during the first three weeks of Ramazan as compared to the three weeks proceeding Ramazan."
"In Baghdad, Operation Together Forward has made a difference in the focus areas, but has not met our overall expectations of sustaining a reduction of levels of violence."
Against this backdrop of increased violence, the debate over the war is heating up in Washington, forcing an unusual admission from US President George W. Bush that the situation is in some ways comparable to Vietnam in 1968.
Bush was asked if he agreed with a New York Times columnist's comparison of the strife in Iraq with the Tet Offensive, which became seen as the tipping point in America's most famous defeat.
"He could be right," Bush told ABC news. "There's certainly a stepped-up level of violence."
US strategy has long been to build up Iraq's government and security forces until they are able to contain extremist elements, but this year's outbreak of sectarian violence has exposed serious failings in Iraqi units.
Police units especially have been accused of collaborating with the Shia sectarian militias which US commanders now describe as the biggest single threat to Iraq's future.
Now, Prime Minister Nuri al-Maliki's own determination to fight the militias is also in question, after he ordered US forces on Wednesday to release a Shia militant detained on suspicion of running a death squad.
Meanwhile in the southern city of Amara "rogue elements" of radical cleric Moqtada al-Sadr's Mahdi Army militia fought a pitched battle with Iraqi police, forcing the Iraqi Army to send reinforcements into the town.
"Three gunmen and four civilians were killed, and 35 people are wounded, including police, insurgents and civilians," said Zamil al-Oreibi, medical director of the city healthy department.
"There are more police casualties, but they have not been recovered yet. The fighting is still going on," he added.
Military spokesman Major Charlie Burbridge said British forces were on stand-by to support the Iraqi troops if needed.
In other violence, five people were killed, including two police, in a bomb attack against a police convoy, and Brigadier General Kadhim Mahdi of the border police was assassinated in the south Baghdad neighbourhood of Saidiyah.
Across Diyala province, aside from the blast in Khalis, north-east of Baghdad, nine people were killed in separate incidents.

Copyright AFP (Agence France-Presse), 2006