A suicide bomber driving a car packed with explosives killed at least 12 people who had gathered to buy and sell cars in Iraq on Thursday, local officials said.
No group immediately claimed responsibility for the attack, which took place near the car markets in the town of Balad Ruz, in northeastern Iraq, injuring another 25 people.
However, suicide bombings are the hallmark of Al Qaeda, whose Iraq affiliate has re-emerged, invigorated by the civil war in Syria and growing resentment among the country's Sunni Muslim minority towards the Shia-led government.
Two years after the withdrawal of US troops from Iraq, violence is at its highest levels since the sectarian bloodshed of 2006-7, when tens of thousands of people were killed.
A sticky bomb attached to a mini bus went off killing four people in the northern Baghdad's mainly Shia district of Sha'ab, police said.
Earlier on Thursday, a roadside bomb exploded inside a street market killing four people and wounded another 11 in the town of Latifiya, south of Baghdad, police said.
Special forces fighting Al Qaeda linked militants in Fallujah
Iraqi special operations forces on Thursday entered the city of Fallujah, half of which is reportedly under the control of militants linked to Al Qaeda.
"We entered Fallujah with heavy clashes," Major General Fadhel al-Barwari said in an online statement, without providing further details.
An interior ministry official said earlier that half of Fallujah, a city west of Baghdad, was under the control of fighters from Al Qaeda-linked group the Islamic State of Iraq and the Levant (ISIL).
A witness said that militants had set up checkpoints, each manned by six to seven people, in central and south Fallujah.
Police in the city abandoned most of their positions on Wednesday and militants burned some police stations, seized weapons and freed more than 100 prisoners, officers said.
Clashes reported in Ramadi after removal of protest camp
And in eastern Ramadi, fighting erupted between tribesman and police on one side and militants on the other, police said.
Clashes began in the Ramadi area on Monday as security forces tore down the country's main Sunni Arab anti-government protest camp near the city west of Baghdad, and continued for two days.
The fighting in Ramadi later wound down with militants still in control of some areas.
On Wednesday, militants and security forces in Ramadi clashed sporadically, with four police stations torched, the AFP journalist said.
Maliki had long sought the removal of the protest camp, calling it a "headquarters for the leadership of Al Qaeda," but doing so resulted in a sharp decline in the security situation.
While the camp's closure has removed a physical sign of deep-seated grievances among Sunni Arabs, their complaints of being marginalised by the Shia-led authorities and unfairly targeted by security forces remain unaddressed.
There has also been political fallout, with 44 MPs, most of them Sunni, announcing on Monday that they had submitted their resignations.
More than 8,000 people were killed in violent actions in Iraq last year, the United Nations said.