Updated

U.S. soldiers killed 14 insurgents in two days of fighting in a strategic northern city, the American military said Monday, and gunmen killed 10 Iraqi soldiers in the central Sunni heartland.

A hard-line Sunni clerical group accused Iraqi government commandos of torturing and killing 10 Sunni Arab civilians in Baghdad, fueling sectarian tensions between the country's two major religious groups.

Soldiers of the U.S. 3rd Armored Cavalry Regiment killed four insurgents in a gunbattle Sunday, and 10 more were killed Monday as fighting raged in Tal Afar (search), 260 miles north of Baghdad, the U.S. command reported. American troops suffered no casualties, the statement said.

However, insurgents bloodied an Iraqi force in Khalis (search), 45 miles north of Baghdad. Guerrillas firing mortars, machine guns and semiautomatic weapons stormed an Iraqi checkpoint about 5 a.m., killing eight Iraqi soldiers, Khalis police chief Col. Mahdi Saleh said.

About 90 minutes later, a car bomb exploded a few miles away as an Iraqi army patrol passed, killing two soldiers, Saleh said. Two soldiers and three civilians were wounded in the attacks.

Al Qaeda in Iraq (search) claimed responsibility for the attacks in a Web statement, but the authenticity of the posting could not be confirmed. On June 15, a bomber wearing an army uniform blew himself up in an Iraqi army mess hall in Khalis, killing 26 soldiers.

Six civilians were also killed in the Tal Afar fighting and 22 were wounded, according to the city police chief, Brig. Gen. Najim Abdullah al-Jubouri. Some of the wounded were hospital workers, officials said.

The city is home to Arabs, Kurds and Turkmen and is located along a major road to Syria, which U.S. and Iraqi officials say is a jumping off point for Islamic extremists infiltrating Iraq.

Two U.S. Marines were killed Sunday by "indirect fire" — presumably mortar shells — in the insurgent stronghold of Hit, the U.S. command said. Hit is on the Euphrates River in western Iraq along another major route from Syria.

On Sunday, car bombings and ambushes killed about 60 people in Baghdad and elsewhere. The spike in violence occurred despite an ongoing military operation in the capital, codenamed Lightning, that has sharply reduced homicide attacks in the capital.

Nevertheless, Defense Minister Saadoun al-Duleimi insisted Operation Lightning (search) had been successful and would be followed by other offensives until "we break the back of the terrorists — one after another."

Such operations have curbed insurgent attacks, but have also angered some Sunnis, who claim their neighborhoods have been unfairly targeted by security forces of the Shiite and Kurdish-dominated government. Sunni Arabs form the core of the insurgency.

On Monday, an influential Sunni clerical organization accused Iraqi security forces of detaining, torturing and killing 10 Sunnis in Baghdad. Government officials had no comment, but a doctor at Yarmouk hospital confirmed receiving the bodies, which he said showed signs of abuse. The doctor spoke on condition of anonymity, fearing reprisal.

The Association of Muslim Scholars said members of an Interior Ministry commando brigade detained the men Sunday as they visited relatives in Baghdad's predominantly Shiite neighborhood of Shula.

"The men were taken to a detention center where they were tortured, then locked in a container where they suffocated," the association said.

However, the doctor said one of the men was killed and the other nine detained after the troops came under fire Sunday in Shula. Defense Ministry officials declined comment, referring queries to the Interior Ministry. An Interior Ministry official said he had no immediate comment.

Also Monday:

— U.S. and Iraqi officials signed four economic agreements in Amman, Jordan at the end of talks headed by Undersecretary of State Robert Zoellick to boost reconstruction in Iraq.

— Iraq's Foreign Minister Hoshyar Zebari said Egypt's top envoy did not make any illegal or inappropriate contacts with insurgents in Baghdad. The statement came as Iraq tried to mend a rift with Egypt after Iraqi officials suggested slain envoy Ihab al-Sherif may have been meeting with Iraqi insurgents before he was kidnapped July 2.

— Two of the 15 Sunni Arabs on a committee drafting Iraq's constitution have quit after receiving threats, committee members said.