BAQOUBA, Iraq - U.S. and Iraqi troops captured two senior al Qaeda militants and seven other operatives Saturday in Diyala province, an Iraqi commander said, as an offensive to clear the volatile area of insurgents entered its fifth day.

The U.S. military also cracked down elsewhere in Iraq, saying in a statement that seven other al Qaeda fighters were killed and 10 suspects detained in raids in Tikrit, east of Fallujah, south of Baghdad and in Mosul.

Three other militants suspected of having ties to Iran were detained in a predawn operation by U.S. forces working with Iraqi informants in Baghdad's main Shiite district of Sadr City, the military said separately.

The Americans have accused Tehran of providing mainly Shiite militias with training and powerful roadside bombs known as explosively formed projectiles, or EFPs, that have killed hundreds of U.S. troops in recent months.

"Coalition forces are determined to counter Iranian influence in Iraq, pursuing those suspected of smuggling arms and other forms of lethal aid into Iraq," military spokesman Lt. Col. Christopher Garver said in a statement. "Disrupting the bombing network in Baghdad remains a high priority for us, and we will continue to target the cells' leaders and members."

Roadside bombs, including EFPs and other makeshift devices used by Sunni and Shiite militants alike, are the No. 1 killer of foreign troops in Iraq. At least 20 U.S. troops have been killed in Iraq this week -- all but five from wounds suffered from improvised explosive devices, the term the military uses for roadside bombs.

The British military also said Saturday that a British soldier had died of wounds suffered the day before in a roadside bombing in the southern Iraqi city of Basra. The death raised to at least 153 the number of British troops killed since the war started in March 2003.

Violence also continued to target Iraqi forces.

Gunmen stormed a school building being used by commandos sent to reinforce security in the northern Sunni city of Samarra, killing two officers and wounding six other people, including five civilians, in a 45 minute gunbattle, police and hospital officials said, speaking on condition of anonymity because of security concerns.

The attackers, some masked and armed with rocket-propelled grenades and machine guns, were targeting Iraqi special forces sent to Samarra, 60 miles north of Baghdad, following the most recent bombing that brought down the twin minarets of the revered Shiite shrine there, the officials said.

Six men also were killed after they were seized by gunmen at an illegal checkpoint near the Shiite holy city of Karbala, 50 miles south of Baghdad, according to a member of the provincial council, Ghalib al-Daami. He said those killed included a local council member from the nearby town of Ayn Tamir.

The announcement of the capture of two senior al Qaeda members in Diyala province came after concerns were raised that much of the terror organization's local leadership had fled before a major U.S. military crackdown began on Monday.

The U.S. ground forces commander, Lt. Gen. Raymond Odierno, has said more than three-quarters of Baqouba's al Qaeda leadership fled before the Americans moved into the city in force.

Iraqi Maj. Gen. Abdul Karim al-Rubaie said the suspects had been transferred immediately to Baghdad, but he provided no more information about their identities. Seven other suspected al-Qaida fighters had been arrested in the center of Baqouba, and 30 hostages were released from a prison elsewhere in the provincial capital, al-Rubaie said.

The U.S. military did not immediately respond to a request for comment, but it said in a statement earlier Saturday that at least 55 al Qaeda operatives have been killed and 23 detained since the start of Operation Arrowhead Ripper. It also said 16 weapons caches have been discovered, and 28 roadside bombs and 12 booby-trapped structures have been destroyed.

Earlier this week, creeping house-to-house through western Baqouba, U.S. soldiers made a startling discovery: a suspected al Qaeda field hospital stocked with oxygen tanks, heart defibrillators and other medical equipment.

The find displayed al-Qaida's sophisticated support network in Baqouba, a mostly Sunni town of about 300,000 people, located 35 miles north of Baghdad.

And that may presage great problems in an outright defeat of al Qaeda even if U.S. forces succeed in ousting the group from Baqouba. The city has received little aid or other services from the central government, which feared supplies would end up in al-Qaida hands.

As the al Qaeda field hospital proved, much assistance did bypass residents and found its way to the terrorist organization.

Until trust is mended, U.S. military commanders say, any success they have in this offensive could be lost on a city unable or unwilling to reconcile sectarian differences.

Historically a mixed province, Diyala has become predominantly Sunni as Shiites fled an influx of Sunni militants from Anbar province. The militants were welcomed by many of Saddam Hussein's former Baath party members.

The shifting population balance only increased tension between local Sunni tribal leaders and the Shiite-dominated federal government in Baghdad.

"There are a multitude of systematic functions that aren't working," said Maj. Robbie Parke, 36, spokesman for the 3rd Brigade, 2nd Infantry Division. "The Iraqi government has to say, `Look, Baqouba is in trouble, and we need to help.'"

So far that has not happened, U.S. officials say. But there are signs of hope.

"The (Iraqi) government is very immature, but they're getting better and saying the right things. We've got to hold them to that," said Odierno, the ground forces commander.

He spoke to AP during a trip to Baqouba on Thursday as American forces began in earnest to squeeze al Qaeda, Sunni insurgents and Shiite militiamen after the arrival of the final brigade of an additional 30,000 troops dispatched by President Bush.

Diyala province is one of a quartet of operations targeting militants entrenched in the so-called "belts" of Baghdad -- regions on the capital's flanks where mostly Sunni insurgents are believed to have based car-bomb factories, weapons stashes and militant safe houses.