BAGHDAD, Iraq—A suicide bomber killed 14 police recruits and two policemen in northern Iraq on Thursday, police and military sources said, defying a U.S.-backed Iraqi security crackdown that has sharply reduced violence.
Militants also attacked a U.S.-backed neighbourhood patrol in Tikrit north of Baghdad, police said. At least 12 gunmen were killed in clashes after jumping out of a fuel tanker and firing on the patrol.
The U.S. military announced that 4,000 soldiers, the fourth of five extra brigades sent to Iraq last year to help curb violence, would return home next month. The military has previously said it plans to withdraw the fifth brigade by July.
The five so-called "surge" brigades have been credited with helping to improve security in Iraq and pull the country back from the brink of sectarian civil war. The U.S. military said at the weekend that violence was at a four-year-low.
Prime Minister Nuri al-Maliki highlighted those successes on Thursday at a conference in Stockholm where he basked in praise from international leaders lauding Iraq's economic and political development five years after the U.S. invasion.
He also pressed Iraq's creditors to cancel about $60 billion in debts at the Stockholm conference, but two of its biggest lenders, Kuwait and Saudi Arabia, sent only junior representatives to hear the call.
The conference was the first annual review of the International Compact with Iraq agreed in the Egyptian resort of Sharm el-Sheikh last year, which committed Iraq to implement reforms in exchange for greater international support.
"The deadly strikes that we launched on the terrorist organisation of al Qaeda and outlaws this year have resulted in clear security improvements all over the country," Maliki told the conference.
U.S military and Iraqi officials say al Qaeda is on the run and an offensive in the northern city of Mosul has broken the group's networks in its last urban stronghold in Iraq. But they said the group remains a threat.
A suicide bomber wearing a military uniform detonated an explosive vest near a police recruiting centre where about 200 applicants queued in the town of Sinjar. U.S. and Iraqi officials have blamed al Qaeda for similar attacks in the past.
Ten police recruits and five police officers were also wounded. Sunni Arab insurgents have carried out frequent attacks on police recruits, killing hundreds.
A suicide bomber driving a police vehicle killed two policemen and wounded eight people, including two policemen, in Mosul, 390 km (240 miles) north of Baghdad, police said.
U.S.-backed neighbourhood patrols have helped ease violence to what the U.S. military says is the lowest level in over four years. But they have come under increasing attack.
In Tikrit, north of Baghdad at least insurgents were killed after jumping out a fuel tanker and attacking one of the patrol. A police official said one of the insurgents blew himself up during the attack. He said 12 were killed.
"It was a fuel tanker. There were 14 terrorists inside, including Sudanese and other Arabs," said Ahmed al-Dulaimi, the head of a regional neighbourhood patrol network.
The redeployment of the 4,000 soldiers of the 4th Stryker Brigade from Diyala province, once one of Iraq's most dangerous regions, is part of a Pentagon plan to withdraw 20,000 troops by the end of July.
U.S. President George W. Bush last month suspended further troop withdrawals from July, imposing a 45-day freeze on the remaining 140,000 troops to assess the security situation before considering more cuts.
The top U.S. commander in Iraq, General David Petraeus, has repeatedly stressed that security progress is "fragile and reversible."