The U.S. military faced complaints from its Sunni allies over claims that more civilians had been killed by American forces — amplifying tensions as the Pentagon tries to calm anger over an airstrike last week that claimed innocent lives.

The disputes have further strained ties with anti-Al Qaeda fighters considered crucial in turning the tide against extremist violence.

The latest deaths occurred Tuesday when U.S. soldiers — acting on tips — stormed a squat, mud-brick house in the village of Adwar, 10 miles south of Saddam Hussein's hometown of Tikrit. The predominantly Sunni area is home to many former members of Saddam's regime, and has been the frequent site of American raids.

The U.S. military said a gunbattle broke out after the troops came under small-arms fire by two suspected terrorists. It acknowledged a woman was killed and a child was wounded, but said it was not clear who shot them.

Two other men were killed and the military described them as insurgents.

But Iraqi police, relatives and neighbors said a couple and their 19-year-old son were shot to death in their beds. Iraqi police also said two girls were wounded and one later died. AP Television News video showed the doors pockmarked with bullet holes and pillows and other bedding on the floor and soaked with blood.

It was the second time in as many days that the U.S. military conceded involvement in the death of Iraqi civilians.

On Monday, the military said it had accidentally killed nine Iraqi civilians, including a child, in an airstrike Saturday targeting Al Qaeda in Iraq south of Baghdad.

The killings illustrate the increasing difficulty in identifying the enemy as the nature of the U.S.-led war in Iraq has changed. Many former insurgents and tribal leaders have joined forces with the Americans against Al Qaeda in Iraq. The mistaken shootings also threaten to jeopardize the fragile relationship between the Americans and their new Sunni partners.

"Such acts by U.S. soldiers cannot be justified and they will create mistrust and arouse suspicions between U.S. Army and members of the awakening councils," said Abu Muthanna, a leader of a U.S.-backed anti-Al Qaeda group in the northern Baghdad neighborhood of Azamiyah. "This could hurt the level of cooperation between the two sides."

Both U.S. raids on Saturday and Tuesday were based on what the military said was intelligence gleaned from informants. That raised the possibility that the military was misled into targeting the households, perhaps as part of an insurgent campaign to derail the U.S.-backed Sunni revolt against Al Qaeda in Iraq.

In Tuesday's incident, the U.S. military said it "regrets the loss of an innocent civilian and the wounding of a child." It said U.S. soldiers killed the two men in self-defense.

But the head of Adwar's Awakening Council, Col. Mutasim Ahmed, said that one of the men killed was a U.S.-allied fighter and said it appeared that gunmen were positioned near the house and attacked the Americans, provoking return fire.

"Our own investigation is continuing and this area is full of Al Qaeda operatives who are not satisfied with our successful work with the Americans," he said. "I cannot rule out that the enemy is trying to sow seeds of division between us and the Americans."

He vowed to keep up the fight against Al Qaeda, but said his fighters would break their alliance with Americans if civilian deaths continued.

"Such actions could have a negative impact on our joint work to root out Al Qaeda," he warned.

Kareem Talea Hamad, a cousin of one of those killed Tuesday, said he watched the raid from his house across the street, and gave an account that differed from the American military's initial reports.

Hamad said U.S. soldiers opened the house's door and opened fire at once, killing its unarmed residents: father Ali Hamad Shihab, 55, his wife Naeimah Ali Sulaiman, 40, and their son Diaa Ali, who was a member of the local Awakening Council.

Two other daughters were wounded and taken to hospitals, and one died Tuesday morning, Hamad said. An Iraqi police officer, speaking on condition of anonymity because he wasn't authorized to release the information, supported Hamad's account.

A surviving daughter, Nawal Ali, 16, said that she was in the house at the time of the raid, and that an Iraqi interpreter working for U.S. forces tried to stop the American soldiers from killing her parents.

The unidentified interpreter rushed into the house after he heard gunshots, Ali said. "He shouted at the Americans, saying `What the heck are you are doing?"' she said, adding he then pushed the troops away from the children.

American and Iraqi commanders say the Sunni uprising has helped drive Al Qaeda from the belts around Baghdad and forced extremists to hunt for new havens in northern Iraq. As areas have been cleared, more evidence of the brutality of the terror network has been uncovered.

U.S.-backed tribesmen discovered about 50 bodies Tuesday in a mass grave in a former al-Qaida stronghold of Jazeerah near Lake Tharthar, an area northwest of Baghdad where hundreds of bodies have been unearthed in recent months, said Col. Mazin Younis Hussein, commander of a Samarra police unit.

Some of the bodies were severely decomposed, suggesting they were buried months ago, while others appeared to have been killed recently, said police Lt. Muthanna Shakir, who visited the site.

The U.S. military said it had no information about the discovery.

A suicide bomber also struck the convoy of a sheik working with U.S. forces Tuesday in Taji, 12 miles north of Baghdad, killing his nephew and another follower, police and the sheik said.

In a separate development, a new Iraqi flag — without the three green stars of Saddam Hussein's ousted Baath party — was hoisted Tuesday over the Iraqi Cabinet building in Baghdad in a symbolic break with the past.

The Iraqi Oil Ministry accused Iran of overpumping in a shared field about 200 miles southeast of Baghdad.

An official at Iraq's South Oil Company, which is controled by the ministry, claimed Iran was pumping oil from their portion of the al-Fakkah field at such high rates that nine of 22 wells in Iraqi territory have been left inoperable. He further said the Iranians are blocking Iraqi repair crews from reaching the nine wells.

The official spoke on condition of anonymity because of the sensitive nature of the information.

On Monday, the state-run al-Sabah daily said Iraq's Foreign Affairs Ministry had sent a protest note to Tehran.