American and Iraqi troops battled the country's most powerful Shiite militia in a southern city, killing 30 fighters, amid increasing friction between the Mahdi Army and U.S. forces trying to put an end to Iraq's bloody sectarian killings.

The clash, which lasted for several hours and saw a U.S. Abrams tank damaged by a barrage of rocket-propelled grenades, was the second with the Mahdi Army in the southern city of Diwaniyah in as many months.

It came as the United States has shown increasing impatience with the Iraqi government's inability to stop militias responsible for escalating sectarian violence, which American commanders have warned is leading toward civil war.

CountryWatch: Iraq

U.S. troops have been increasingly involved in the effort to stop U.S. troops have been increasingly involved in the effort to stop the killings, particularly in Baghdad, where since August U.S. and Iraqi forces have been carrying out a neighborhood by neighborhood sweep to clear the capital of weapons and fighters.

The sweep has brought a bulge in U.S casualties. In the first seven days of this month, 26 U.S. troops have been killed in combat, at least 16 of them in Baghdad. In the latest deaths, the military said two soldiers were killed Saturday, one in the capital. The location of the other's death in a bomb attack was not announced.

In perhaps a better gauge of the intensity of the combat, in an age where body armor and quick access to medical care from the battlefield limits combat deaths, September saw 776 U.S. troops wounded, the highest of any month since U.S. troops stormed the insurgent stronghold of Fallujah in November 2004, when there were nearly double that number.

At least 14 Iraqis died in other violence around the country Sunday, including a Shiite woman and her young daughter who were killed when gunmen opened fire on their minivan in Baqouba, northeast of Baghdad. The driver also was killed, and the woman's husband and her brother were wounded.

Police also found 51 bullet-riddled bodies in various parts of Baghdad during a 24-hour period ending Sunday morning, police 1st Lt. Mohammed Khayoun said, all apparent victims of the sectarian death squads that roam the capital, with many of the bodies showing signs of torture.

U.S. Secretary of State Condoleezza Rice gave Prime Minister Nouri al-Maliki and other Iraqi leaders a blunt assessment during a visit this week, telling them the violence cannot be tolerated and they have to act. After his own visit to Iraq, Sen. John Warner gave a starker warning, that if violence is not stopped within two or three months, Washington should make "bold decisions" on what to do next.

But critics accuse al-Maliki of hesitating to take action against Shiite militias because of their links to parties in his government.

The Mahdi Army, which Sunnis accuse of many of the sectarian killings, is run by the party of radical Shiite cleric Muqtada al-Sadr, which holds 30 of the 275 seats in parliament and five Cabinet posts, and the cleric's backing helped al-Maliki win the top job earlier this year.

U.S. troops have been quietly launching raids on key al-Sadr loyalists and Mahdi Army members in the past week, members of al-Sadr's party say. The U.S. has announced numerous arrests during the Baghdad sweep, but does not specify what group they belong to so exact numbers could not be attained.

Al-Sadr loyalists accuse the Americans of trying to pick a wider fight. U.S. troops and the Mahdi Army had major battles twice in 2004.

"The Americans are creating pretexts to provoke us and drag us into confrontation," said Fadhil Qasir, a spokesman for the Mahdi Army in Diwaniyah.

The fighting in Diwaniyah, 80 miles south of Baghdad, broke out after U.S. and Iraqi troops entered the city looking for Mahdi Army members responsible for the execution-style killings of 11 Iraqi army troops in August. The slayings provoked a fierce fight at the time between the Mahdi Army and Iraqi forces that left 23 Iraqi troops and 50 militiamen killed and scores more wounded.

On Sunday, militiamen attacked coalition forces after they raided the house of Kifah al-Greiti, a Mahdi Army commander in the city in the early morning hours, Iraqi Army Capt. Fatiq Ayed said.

A fierce battle broke out, lasting into late Sunday morning. Fighting could be seen in two neighborhoods and heavy explosions could be heard, eventually stopping by midmorning.

The U.S. military said up to 10 teams of militiamen with rocket propelled grenades attacked Iraqi and U.S. troops. An M1A2 Abrams tank was struck by multiple RPG rounds and was severely damaged, the military said.

Later, U.S. troops barricaded off entrances to the area to prevent militia reinforcements from entering. The military said 30 militiamen were killed, with no casualties among the U.S. or Iraqi forces.

The troops were after a "high-value target" involved in killing the Aug. 28 killing of the Iraqi army soldiers when they came under attack, the U.S. command said in a statement without identifying the target.

It said the target was captured along with three other people.

Iraqi police Lt. Raed Jabir and Qasir, of the Mahdi Army, al-Greiti was not arrested, and it was not clear who the captured target was. Qasir and other al-Sadr loyalists said no Mahdi Army fighters were killed.

Sheik Abdul-Razzaq al-Nadawi, the head of al-Sadr's office in Diwaniyah, said the movement had negotiated an arrangement with the prime minister's office that U.S. troops would not enter Mahdi Army neighborhoods in Diwaniyah, and that the presence of U.S. troops overnight had provoked the clashes.

"We don't attack, but when we are attacked, we respond," he said.

In other attacks Sunday, according to police:

— A roadside bomb killed an Iraqi police colonel outside the northern city of Mosul.

— Gunmen killed another man near his house in Mosul.

— Mortar fire killed a civilian in Musayyib, 40 miles south of Baghdad.

— A roadside bomb killed four people on a highway near Tikrit, north of Baghdad.

— A bomb in Baghdad killed a policeman.

— A homicide bomber blew himself up outside a hospital in Muqdadiyah, about 60 miles north of Baghdad, killing two Iraqi soldiers and wounding 11.

— Gunmen on a motorcycle shot dead Sheik Ali Abdul Hussein dead, head of a charity group linked to the Shiite Fadila party in the southern city of Basra.

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