BAGHDAD, Iraq, (AP) – At least two more policemen were murdered early Tuesday in the southern Iraqi city of Amarah, where militiamen loyal to an anti-American cleric have been hunting down officers aligned with a rival group in a new outbreak of Shiite-on-Shiite revenge attacks.

A U.S. military spokesman said there had been no word on the fate of a U.S. Army solider reported missing in Baghdad on Monday. Troops carrying photos of the missing soldier continued door-to-door searches while Army Kiowa reconnaissance helicopters circled overhead in the central Karradah district.

The missing soldier’s name and other personal details have not been officially released. American troops who raided Baghdad’s al-Furat TV on Monday said they were looking for an abducted American officer of Iraqi descent who had gone to join family members in Karradah.

“We have not heard anything,” Lt. Col. Christopher Garver, an American spokesman in Baghdad, said Tuesday. “We are sure U.S. forces are doing everything they can in the search.”

A U.S. military official in Washington on Monday said the missing soldier was a U.S. Army translator of Iraqi descent who may have been abducted. The official spoke on condition of anonymity because the information was not cleared for release.

Police captain Hussein Salih Hassan was killed Tuesday in a pre-dawn gunbattle with attackers who forced their way into his home, Ali Challoub, an administrator at Amarah’s al-Sadr Public hospital, said. A noncommissioned officer, Ala’ Ghlayyim Zned was killed in his home by machine gun-toting attackers at around the same time, Challoub said.

The latest killings in Amarah follow the murders of four policemen on Monday, which were blamed on fighters of the Mahdi Army headed by hardline anti-American cleric Muqtada al-Sadr. Those forces appeared to have control of the southern city’s streets after the police force dominated by the rival Badr Brigades fled. Although the Iraqi army set up a few roadblocks, troops did not seek to block Mahdi fighters.

The spread of revenge killings among Shiites in their southern heartland poses a new challenge for the Iraqi government and American forces struggling to control insurgent and sectarian bloodshed to the north — especially in Baghdad. It also bodes ill for greater political progress; both al-Sadr’s party and the sponsors of the Badr Brigades, the Supreme Council for the Islamic Revolution in Iraq, or SCIRI, are members of the ruling Shiite coalition.

The attacks came despite a public call by al-Sadr to halt the killings, suggesting that splinter groups were developing within his militia.

Al-Sadr repeated those calls in an address to supporters Tuesday marking the beginning of the three-day festival of Eid al-Fitr, which marks the end of the holiday fasting month of Ramadan. Sunni Muslims marked the start of the festival on Monday. Celebrations in Baghdad were muted due to fears over the capital’s worsening security situation.

“I totally reject any Shiite-Shiite fighting or Sunni-Shiite sectarian fighting in Iraq under any pretext,” al-Sadr said. “Protecting Iraq is our main goal and the expulsion of the occupation troops from the country is our objective too.”

The conflict in Amarah claimed the lives of 25 police and Mahdi Army fighters late last week when the militia stormed into the city seeking revenge for the kidnapping of the brother of its local commander.

Following two days of relative calm, Mahdi fighters began targeting Badr Brigades-aligned policemen on Monday, while Badr Brigades fighters beheaded the kidnapped nephew of the slain Mahdi commander.

As with most religious occasions in Iraq, the Eid al-Fitr observances were laden with political overtones.

In an address to hundreds of supporters following morning prayers, the head of SCIRI praised a recently passed federalism law that Sunnis fear could divide Iraq into three mini-states and cut them off the nation’s oil wealth.

“Those who oppose and attack this project … are either wrong with good intentions, or deluded, or ignorant or enemies of the Iraqi people and do not want good for Iraq,” Abdul-Aziz al-Hakim said.

Underscoring security concerns, al-Hakim spoke from behind a screen of bulletproof glass surrounded by bodyguards at the party’s Baghdad headquarters.

Hoping to find a political solution to the ongoing violence, the Bush administration has asked the government of Prime Minister Nouri al-Maliki to issue an unconditional amnesty to Sunni Muslim insurgents, according to politicians close to the country’s prime minister and President Jalal Talabani.

They said U.S. officials were engaged in ongoing talks with members of the insurgency, including members of Saddam’s outlawed Baath Party, to find a way to end fighting that has plagued American forces in Baghdad and the sprawling Sunni heartland of Anbar province to the west.

Members of al-Qaida in Iraq are not included in either the talks or the U.S. amnesty proposal, which would require Iraqi government approval that is by no means certain.

The Bush administration said Monday there were no plans for dramatic shifts in policy or for ultimatums to the Iraqi government to force progress.

The U.S. ambassador to Iraq, Zalmay Khalilzad, and Gen. George Casey, the top U.S. commander there, were scheduled to hold a rare joint news conference Tuesday.