Updated

A homicide bomber blew himself up Thursday in a crowd of police recruits in northwestern Iraq, killing at least 16 men and wounding 14 others, an official said.

The blast occurred in Sinjar, a town near the Syrian border that was the site of the deadliest attack of the war — a series of homicide truck bombings that killed an estimated 500 people.

Nobody has claimed responsibility for the latest attack. But it bore the hallmarks of al-Qaida in Iraq, underscoring Iraqi claims that insurgents have fled to remote areas to escape a U.S.-Iraqi offensive under way in Mosul, about 74 miles east of Sinjar.

The top official in Sinjar, Dakhil Qassim, said the casualties would have been higher, but the security services had received tips that police recruiting centers would be targeted and had issued a warning on Wednesday advising people to stay away.

But a crowd still gathered at the center in Sinjar. Those killed included 14 recruits and two policemen, while 14 other people were wounded, Qassim said.

"We told them that there (was) no more recruiting for security reasons," Qassim said. "But people gathered at recruiting center anyway hoping that some official might register their names."

Despite the risks, jobs in the police force are prized in areas of the country where unemployment runs high.

Sinjar is dominated by Yazidis, a small Kurdish-speaking sect whose members are considered to be blasphemers by Muslim extremists.

The U.S. military blamed al-Qaida for the Aug. 14 bombings that devastated nearby villages and killed some 500 people.

U.S. and Iraqi forces have met relatively little resistance during the operations in Mosul, although there have been sporadic attacks. Commanders have said they believe insurgent leaders had fled to neighboring areas and would try to regroup.

Another homicide bomber driving a police vehicle struck Iraqi commandos earlier Thursday in Mosul, killing three of them and wounding nine other people, according to battalion commander Capt. Aziz Latif.

The victims were from a unit sent from the southern city of Kut to participate in the Mosul crackdown, Latif said.

The operation in Mosul is one of three recently launched by the U.S.-backed Iraqi government in a bid to clamp down on violence in the country. The other two have focused on Shiite extremists in the southern city of Basra and Baghdad's Sadr City district.

Despite continuing attacks, death tolls among Iraqi civilians and U.S. troops have dropped sharply in Iraq this month. An average of 17 Iraqis have been killed by violence each day this month, the lowest level since December 2005, according to an Associated Press tally.

At least 20 U.S. troop deaths have been recorded so far this month, putting May on track to be the lowest monthly toll this year, an AP count shows.

Al-Maliki touted his government's security and economic progress at a U.N. conference in Stockholm, Sweden.

"Iraq has achieved major success in the battle against terrorism with the support of the international community," he said.

The British Embassy in Iraq, meanwhile, renewed appeals for the release of five Britons kidnapped in Baghdad a year ago Thursday.

The men — four security workers and a consultant — were visiting the Iraqi Finance Ministry compound when they were seized by about 40 gunmen in police uniforms and driving official vehicles.

At the time, Iraqi officials blamed factions of the Mahdi Army, the feared militia of anti-U.S. Shiite cleric Muqtada al-Sadr. However, al-Sadr's followers disavowed the kidnapping and suspicion was cast on so-called splinter groups that the United States believes are controlled by Iran.

In December, the purported kidnappers of the Britons appeared on a video and demanded that Britain pull all its forces from Iraq. A man believed to be one of those kidnapped also was shown seated beneath a sign reading "the Islamic Shiite Resistance in Iraq."

In October, the U.S. military said a raid in Baghdad's Sadr City netted three suspected Shiite militia fighters believed to be responsible for the kidnapping.

"It has been a long and extremely difficult year for these men's families, who only wish to have their loved ones back home, safe from their ordeal," British Ambassador Christopher Prentice said in a statement.

Family and friends of the hostages also appealed for their releases on Thursday in interviews with the British Broadcasting Corp. But they were identified only by their given names in line with a British government policy of not confirming the full names of the captives or their families for security reasons.

A woman identified only as Caroline, who said she is the sister-in-law of a hostage called Alan, pleaded with the captors to release the group.

"A year is far too long for these men's families to be without them, and as fellow human beings, surely you can empathize with what their families are going through. So please, please, send them back," Caroline said in comments to the BBC.