The Iraqi government indefinitely postponed the much-anticipated national reconciliation conference.
A brief statement from the Ministry of State for National Dialogue says only that the Iraqi political powers conference planned for Saturday had been put off for emergency reasons.
Kirkuk's police chief, Major General Torhan Yussef, said 11 people were killed and 62 wounded in a wave of explosions in the northern oil hub.
In one of the attacks, a bomber detonated a car laden with explosives in front of a school that trains young women to become teachers, killing two of the students and wounding 25 more.
Another suicide attack killed five members of an Iraqi armed security detail set up to protect government offices, and a third ripped through a crowded street market.
Meanwhile, details emerged about revenge killings between rival Sunni and Shiite gangs north of Baghdad over the weekend that left at least 54 people dead, and perhaps killed as many as 89.
The slaying of 14 Shiites on Friday by an al-Qaeda-linked group prompted a reaction from Shi’ite militias that resulted in at least 40 dead, the deputy provincial governor Abdullah Hussein Jabarah told news agency AFP.
Sunni civilians were kidnapped from fruit markets and dragged out of hospital beds before being found shot dead in nearby fields.
Iraqi and US forces have surrounded the area to prevent further killings.
In Baghdad itself, a spate of bombings killed 10 more Iraqis, while more bodies of victims of Iraq's sectarian death squads were found in the city's streets or floating in the Tigris River.
Interior ministry spokesman Brigadier General Abdel Karim Khalaf said Hala Mohammed Shakr, head of the interior ministry's financial department, escaped unscathed when two bombs exploded near his convoy, but five bystanders and two bodyguards were killed.
The US military also announced the deaths of three US soldiers in southern Baghdad when a roadside bomb destroyed their vehicle on Saturday, adding to a dramatic rise in US military casualties in Iraq this month.
Pilgrims throng Najaf shrine
Najaf, so often in the past the target of bomb attacks, bucked the trend with hundreds of thousands of pilgrims commemorating the death of Imam Ali in relative safety.
Devotees packed the city under heavy security at the golden-domed shrine to the imam, one of the sect's pivotal figures.
Carefully organised city services were ready for the massive influx from across Iraq and neighbouring Iran to funnel them to the shrine.
Pilgrims paid their respects, kissing the doorways and walls of the shrine itself, before making prayers and vows to the founder of the Shi’ite sect, who was assassinated in 661 AD.
"I am happy and stunned," said Mohammed Jawad, a 36-year-old journalist from the southern city of Basra. "There were huge numbers of people performing their rituals without incident. I was amazed at the organisation."
All traffic in the old city was banned, and pilgrims were ferried from outlying checkpoints to the shrine by specially marked cars to reduce the risk of car-bomb attacks.
"The ceremonies went off as planned without any incident on a security and organisational level," said Najaf deputy governor Abdul Hussein Abtan.
"There were a million pilgrims according to the figures of the transportation people," he added. "The popular committees did an excellent job of protecting the pilgrims and providing services."
Iranian pilgrim Gholam Redha, a 50-year-old civil servant who also came to Najaf last year, said the ceremony was much better organised this time.