A suicide attacker has killed at least 12 people at a tribal council meeting in a government building in Karma, a town near Falluja, Iraqi police said.
At least 30 people have been killed in two bombings in Iraq.
More than a dozen people were wounded in the blast, police added.
The first occurred in the town of Karma, west of Baghdad, where a suicide attacker detonated a bomb at a local council meeting, killing at least 12.
Karma is in the mainly Sunni Muslim province of Anbar, formerly a centre of the anti-US insurgency but which has recently seen a drop in violence.
More than a dozen people were wounded. It was the third attack in a week against a local administrative branch of the US-backed Iraqi government.
It is the third attack in a week against a local administrative branch of the US-backed Iraqi government.
Hours later, a car bomb in the northern city of Mosul left at least 18 people dead and dozens wounded.
Police were quoted as saying the bomber entered the municipal government building through a back door, but it was unclear how he managed to evade security for the meeting.
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It has gotten quieter, but that doesn't make these losses any easier. US military spokesman Steve Stover Local Sunni tribal leaders here and elsewhere have turned against al-Qaeda militants as part of the so-called Awakening movement.
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The attack comes days before US troops are to hand over security responsibility to Iraqis in Anbar.
Earlier on Thursday, the US military said one soldier was killed by a roadside bomb in eastern Baghdad, bringing to at least eight the number of American troops killed in Iraq this week.
The soldier was killed by what is known as an explosively formed penetrator - a powerful bomb believed to come from Iran and which is frequently used by Shia extremists.
"The level of violence has dropped dramatically," said US military spokesman Lt Col Steve Stover. "It has gotten quieter, but that doesn't make these losses any easier."
But he said militants "are constantly thinking of ways that they can undermine us, undermine the government, undermine the Iraqi security forces".
Airport clash
Three suspected militants died on Wednesday after they had opened fire at a US military convoy from a vehicle near Baghdad's international airport, the military said.
However, Iraqi security sources at a west Baghdad hospital said the three, two of whom were women, were bank employees.
Troops opened fire at the vehicle, which crashed and exploded, killing all three passengers.
Four Americans and seven Iraqis were killed on Tuesday in a bombing at a municipal council office in the Shia area of Sadr City in Baghdad.
The US military blamed that attack on infighting between rival Shia Muslim groups.
Another two Americans were shot dead on Monday when a gunman opened fire on a municipal building in Madain, in an attack attributed to a disgruntled official.
Three US soldiers and an Iraqi interpreter were also killed late on Tuesday by a roadside bomb in Ninevah province, an area of intense Sunni extremist activity.
The figure for US military dead is 26 so far in June - less than the average last year but more than the 19 who died in May, the lowest monthly tally since the 2003 US-led invasion of Iraq.
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