BAGHDAD, Iraq -

Four Iraqi soldiers have been accused of raping a 50-year-old Sunni woman and the attempted rape of her two daughters in the second allegation of sexual assault leveled against Iraqi forces this week, an official said Thursday.

Brig. Gen. Nijm Abdullah said the attack allegedly occurred about 10 days ago in the northern city of Tal Afar during a search for weapons and insurgents.

A lieutenant and three enlisted men denied the charge but later confessed after they were confronted by the woman, a Turkoman. Abdullah said a fifth soldier suspected something was wrong, burst into the house and forced the others at gunpoint to stop the assault.

"They have been referred to the judicial authorities so they can receive their just punishment," said Abdullah, who effectively serves as mayor of the city.

A tribal leader from Tal Afar, Sheik Mohammed Khalil Hanash of the Hawyat clan, said the alleged attack took place on Feb. 8. He said the woman told him that the lieutenant filmed the alleged attack on a cell phone video camera, but did not take part.

A second rape allegation within a single week is likely to undermine further the reputation of Iraq's security services, which the U.S. hopes can take over from coalition troops so the Americans and their allies can go home.

The report follows an allegation Monday by a 20-year-old Sunni woman that she was raped by three Iraqi policemen after she was detained during a search of her house in western Baghdad. She was taken to a police garrison where the attack allegedly occurred Sunday before she was rescued by U.S. soldiers, she said.

The government of Prime Minister Nouri al-Maliki cleared the policemen after an investigation lasting less than a day and accused Sunni activists of fabricating the allegation to undermine support for the security forces during the ongoing Baghdad crackdown.

But the woman's complaint and the speed with which the officers were cleared unleashed a political storm, with Sunni politicians accusing the Shiite-led government of a cover-up. U.S. authorities have launched their own investigation.

The chief U.S. military spokesman in Baghdad, Maj. Gen. William B. Caldwell, said Wednesday that the woman had been taken to a U.S.-run medical facility in Baghdad and that Gen. David Petraeus, the new top U.S. commander in Iraq, had ordered his own investigation.

But Caldwell clarified his remarks Thursday, saying the U.S. military was not conducting an independent probe. He said Petraeus has ordered that any evidence pertinent to the case be secured and preserved "so that it may be provided to the appropriate Iraqi judicial official in accordance with U.S. policy."

Rape is considered an especially heinous crime in this conservative, tribal Muslim society and victims rarely speak about it publicly, fearing shame and even death at the hands of male relatives seeking to save the family honor.

Isobel Coleman, director of the Women and Foreign Policy program at the U.S.-based Council on Foreign Relations, said she believes rape is widespread in Iraq's deepening sectarian battles.

The woman in the Tal Afar case appeared Thursday on Al-Jazeera television, saying the soldiers asked her about certain individuals and accused her of lying to them when she insisted that she did not know them.

"They threatened me that if I did not cooperate they would ... cause me a scandal," she said.

Asked why she did not report the attack immediately, she replied: "Who do I complain to? No one allows us to complain."

Abdullah would not say whether the accused soldiers were Shiites or Sunnis, saying only that they came from the southern part of the country, which is Shiite majority. Some Shiite lawmakers said at least two of the three accused in the Baghdad case were Sunni Arabs.