A suicide bomber killed 16 Iraqis on Thursday outside a police station in an area of northern Iraq contested by Kurds and Arabs.
The bomber struck alongside police recruits in the town of Sinjar in Nineveh province. The dead included 14 recruits and two policemen, said Brig. Gen. Khalil Juboori of the provincial police.
An injured policeman said the police had been warned Wednesday of a potential attack and had planned to cancel Thursday's recruitment drive.
"While we were informing recruits not to gather . . . he [the suicide bomber] mingled with the recruits and blew himself up," the policeman said.
Nineveh province's capital, Mosul, has been the focus this month of an Iraqi army and police campaign against fighters aligned with Al Qaeda in Iraq, who have used the city as a stronghold. However, Iraqi forces met little resistance, prompting speculation that most fighters had fled the city before the operation began almost three weeks ago.
The northern city had been a hotbed of violence amid festering tensions between Arabs and Kurds. Nearly 500 people were killed in bombings last August in villages around Sinjar, attacks that were blamed on Al Qaeda in Iraq militants.
Northern Iraq's Kurdistan regional government, which borders Nineveh, wants to incorporate the areas around Mosul as well as Sinjar, which is home to the Yazidi religious sect. The Yazidi leadership is in favor of Sinjar being annexed to Kurdistan.
Nineveh's Sunni Arabs are fiercely opposed to the plan, which the Kurds say would restore to them land that was wrongfully appropriated by Saddam Hussein as part of his policy to settle Arabs in the north and expel Kurds.
Kurds dominate the Nineveh provincial government because Sunni Arabs boycotted the January 2005 elections. The main army division in Mosul consists mainly of Kurds, most of whom served in the Kurds' peshmerga security force.
"There is no doubt that the incident that happened in Sinjar has to do with implementing Article 140," said Kurdish politician Abdul Ghani Yahya, referring to the clause of Iraq's Constitution that calls for settling the status of disputed territories such as Sinjar.
Two car bombs exploded Thursday in Mosul, one in the morning that killed two Iraqi policemen and another in the evening that wounded 12 people, police said.
In Baghdad, gunmen opened fire on Judge Hassan Ali Abdul Hussein while he was traveling by car through the Karada district. Hussein, who sits on Iraq's property claims commission, was wounded in the head and chest, police said.
The commission is supposed to settle Saddam Hussein-era disputes over property, particularly in places such as Kirkuk and surrounding Tamim province, where Kurds were expelled from their homes.
Meanwhile, the U.S. military announced that the fourth of five combat brigades sent to Iraq last year as part of a troop buildup would be leaving Iraq next month. The 4,000 soldiers from the 2nd Infantry Division's 4th Stryker brigade were stationed in Diyala province, a battleground for Shiite Muslim and Sunni Arab militants.
The U.S. military has said the final brigade would redeploy from Iraq by July, leaving 140,000 American troops in Iraq. U.S. commanders will then evaluate what effect the drawdown has had on Iraq's stability.
Army Gen. David H. Petraeus told Congress this month that he was optimistic about being able to call for more troop withdrawals in the fall.
In other developments, Iraqi Prime Minister Nouri Maliki asked his nation's creditors at an international conference in Stockholm to cancel $60 billion in debt dating to Hussein's rule.