Baghdad -- As top Shiite and Sunni Muslim leaders broke their fast together in a show of unity yesterday, a suicide bomber struck in their midst, killing about 25 people and injuring 40 in turbulent Baqouba.
The attack apparently targeted Diyala provincial and tribal leaders who are part of U.S. efforts to forge an alliance against Sunni extremists, who once controlled large parts of Baqouba, about 35 miles northeast of the capital.
Gov. Raad Hameed Tamimi was injured in the blast, which killed the Baqouba police chief, Brig. Gen. Ali Dalyan, and other senior officials, Iraqi security officials said.
U.S. troops were at the meeting, said Lt. Col. Michael Donnelly, a military spokesman based in Tikrit. He said there were casualties but could not confirm figures provided by Iraqi police or say whether they included Americans. The Associated Press reported that two U.S. troops were injured in the attack.
The U.S. military has sought to replicate its progress in Anbar province, where violence fell after an alliance of Sunni tribal leaders revolted last year against the Sunni militant group al-Qaida in Iraq.
A tribal leader, Sheik Abdul-Sattar Abu Risha, was killed in a bombing this month, casting doubt on a strategy that U.S. commanders consider crucial to reducing the number of U.S. troops in Iraq.
No one claimed responsibility for yesterday's attack, which bore the hallmarks of previous ones by al-Qaida in Iraq, a group that has claimed responsibility for killing Abu Risha and other leaders who turned against them.
Meanwhile, Iran closed its border with northern Iraq in an apparent bid to step up pressure for the release of one of its nationals detained by U.S. forces last week, officials in the Kurdish autonomous region said.
The closing of five border posts could halt the flow of food and other essentials into Iraq's northern Kurdish region, the most stable and prosperous in Iraq, said Dana Ahmed Majeed, governor of Sulaymaniya. Leaders of Diyala's government, security forces, major tribes and former insurgents had gathered at a mosque in Shiftah, a mostly Shiite neighborhood, yesterday to discuss ways to ease sectarian tensions and defend the region against extremists.
Witnesses said the bomber detonated explosives strapped to his waist as participants were washing their hands in the mosque courtyard after sharing a meal to break the daylight fast that is a tradition during the holy month of Ramadan.
"We don't know how it happened," Ahmed Kheshali, who attended the meeting, said by telephone. "There were at least three or four checkpoints" to restrict entry.
Police in Diyala said they expect the casualty toll to rise.
The U.S. military has poured troops into Baqouba in a bid to drive out insurgents, who last year declared the city the capital of their self-declared Islamic caliphate and riddled its streets with bombs.
Offensives aided by former insurgents have reduced violence in the city, but tribal leaders say the al-Qaida militants remain entrenched in the surrounding palm groves and continue to stage major attacks on nearby villages.
In other violence yesterday, a suicide truck bomber detonated explosives at a checkpoint run by Iraqi security forces on the road between Mosul and Tal Afar, killing six people and injuring 17, police said.
Police in Baghdad recovered the bodies of 12 victims of execution-style killings.
The U.S. military reported that a soldier was killed by insurgent gunfire yesterday in Salahuddin province, north of the capital.
At least 3,798 U.S. personnel have been killed since the U.S.-led invasion of Iraq in 2003, according to an Associated Press count.
Alexandra Zavis writes for the Los Angeles Times. The Associated Press contributed to this article.