Aftermath of the bomb attacks in Sadr City, Baghdad
More than 50 people have been killed in a series of bomb attacks in Iraq in the worst day of violence since US forces withdrew from urban areas on 30 June.
The most lethal attack was in Talafar, near Mosul, where at least 34 people were killed and more than 60 injured in a double suicide bombing.
In Baghdad, two attacks at markets left at least 16 dead.
Several other people were killed in smaller attacks in the capital and in southern Kirkuk.
The BBC's Gabriel Gatehouse in Baghdad says the attacks raise questions about whether Iraqi forces are capable of guaranteeing security without US support.
Those who want to derail the handover from US to Iraqi forces now appear to be testing the ground to see how much room they have for manoeuvre, he adds.
The attacks in Talafar, which is populated mainly by members of the Turkmen ethnic minority, happened at about 0730 (0430 GMT) and in quick succession.
First, a suicide bomber - who was reportedly wearing a police uniform - detonated his explosives vest. The second blast followed as people gathered at the scene of the first explosion.
The target of the attack appears to have been a member of the local security forces, our correspondent says.
He says this area of northern Iraq is rapidly becoming Iraq's most dangerous region.
On Wednesday, two explosions near Shia mosques in Mosul killed at least nine people and wounded many more.
In Sadr City, a Shia area of Baghdad, two roadside bombs exploded in a market, killing at least seven people and wounding dozens.
The bombs were reportedly placed in rubbish piles in the area.
Later, a double bomb attack at a market in a Sunni neighbourhood in northern Baghdad killed nine and injured 35.
In another attack in the capital, a roadside bomb blast killed one civilian in the central Karrada area, police said.
They said the attack targeted a convoy of Iraq's Central Bank governor, who was unhurt.
US combat troops pulled out from Iraqi towns and cities last week.
US President Barack Obama has described the handover to Iraqis as a milestone, warning that the country's leaders would face "hard choices" on security and politics.
The withdrawal came ahead of the full departure of US forces by 2012.