The U.S. military Wednesday announced it would investigate a Sunni woman's allegations she was raped last weekend by three Iraqi policemen — setting up a possible confrontation with Iraqi Prime Minister Nouri al-Maliki, who has dismissed the story as false.

The move, announced by the military's chief spokesman, may be aimed at containing a growing controversy that could enflame the already high sectarian tensions; Al-Maliki maintains the charge was fabricated by Sunni politicians and extremists to discredit the police and the ongoing security crackdown in Baghdad.

The story hit Monday following a shocking, detailed televised accusation of rape by a 20-year-old Iraqi woman, forcing the issue on al-Maliki, a Shiite, who promised to investigate the case and punish anyone found to be involved in the alleged attack.

Sunnis called for an international investigation, led by Ahmed Abdul-Ghafour al-Samaraie, head of the Sunni Endowments. Al-Samaraie's organization cares for Sunni mosques and shrines in Iraq.

But on Tuesday, al-Maliki reversed himself and released what he said was a medical report indicating no signs of rape.

In his Tuesday statement, al-Maliki also said the woman had three outstanding warrants against her for unspecified charges. He also accused "certain parties" — a thinly veiled reference to Sunni politicians — of fabricating the allegation.

Al-Maliki then announced Wednesday that al-Samaraie was fired. No reason was given.

Al-Samaraie, speaking from Amman in neighboring Jordan, disputed al-Maliki's right to fire him, arguing that only Iraq's Presidential Council — which comprises President Jalal Talabani and his two deputies — has that authority.

In a possible effort to calm debate, the U.S. military decided to step in, announcing Gen. David Petraeus, the new top U.S. commander in Iraq, had ordered his own investigation, appointing an American officer to begin collecting evidence.

"Once the Iraqi government makes a decision on how they are going to move forward, there is an investigating judicial process established and they need this information from us, we will make that readily available to them," chief military spokesman Maj. Gen. William B. Caldwell said.

It began when the woman was detained Sunday by Iraqi police at her west Baghdad home and accused of aiding Sunni insurgents.

She was then taken to a police garrison where she was raped by the three policemen before American soldiers arrived and took her away, she said.

Caldwell confirmed that "an Iraqi woman" was brought to the U.S.-run hospital Sunday evening and released the following morning but refused to give further details or talk about her treatment.

However, the prime minister's office e-mailed news organizations what it said was a U.S. medical report indicating no signs of rape — and al-Maliki announced the policemen should be awarded for bringing the woman in.

The one-page English language form indicated blood and other tests had been performed and included a handwritten note in English stating "no lacerations" or "obvious bruising." The word rape was not used.

Iraqi women rarely report rape because of shame and fear of public scorn. Victims even risk death at the hands of male relatives seeking to purge the family's honor. Some officials, including Sunnis, discounted the woman's claim simply because she came forward publicly.

"What has been said about the woman's rape seems like a fantasy," said Aida Osayran, a Sunni lawmaker and member of parliament's Human Rights Committee. "It is certain that what she says is improper because it is not in our customs and traditions."

Meanwhile, Iraqi officials sought to discredit the claim by casting dispersions on the woman's character.

Brig. Gen. Qassim Moussawi, spokesman for the Baghdad security operations, said the woman had been in an "urfi" marriage, a common-law relationship that is not legally recognized in most Arab countries, and that she knew her husband only by his first name.

Moussawi said the woman was detained in a house which was not hers and that clothing found there was traced to a man whose body was found nearby. He did not elaborate.

Such comments did little to calm the outrage among many Sunnis, who have little confidence in the Shiite-led police forces. Many Sunnis considered the government's speed in clearing the policemen as an insult to their community.

In Mosul, a few hundred Sunni students staged a rare, half-hour rally at the local university campus to demand the government reopen the investigation. Participants by and large accepted the woman's account.

Similar sentiments echoed across the Arab world, especially in Sunni countries deeply suspicious of Iraq's Shiite-led government. Television stations in Egypt and the Persian Gulf have reported extensively on the case since Monday.

Columnist Issa al-Enezi wrote in Kuwait's Al-Siyassah newspaper than "instead of ordering a serious investigation," al-Maliki "rewards the perpetrators alleging the girl was making up the story to foil the security plan."

"Rewarding criminals is encouraging them. It is denying justice and instigating infighting among Muslims. May God help Iraqis put up with their extremist government," al-Enezi wrote.

Rape is considered not only an assault on the victim but a grave offense against her entire family and community. The allegations harkened back to the dark years of Saddam Hussein's rule, when wives and daughters were raped in front of their husbands and fathers to exact confessions from the men.

It is considered especially heinous in conservative Muslim countries, and victims rarely come forward since they risk not only public scorn but possible "honor killing" at the hands of male relations seeking to restore the family's honor.

The Associated Press contributed to this report.