Iraq's Shi'ite-led government says it has not been able to investigate allegations of torture of Sunni Arab prisoners in an interior-run detention center in Baghdad because mistakes made at the site by Americans have tainted some of the evidence and files.

Two weeks ago, Iraq's Shi'ite Prime Minister Ibrahim al-Jaafari ordered an internal investigation of the detainee abuse case and promised a full report by the end of the month.

Sources close to the U.S. investigation of the detainee abuse scandal tell VOA that the Iraqi government now alleges that it has not been able complete its investigation because U.S. soldiers who discovered the detainees had failed to properly handle evidence and secure detainee files.

The U.S. military has repeatedly said that it observed all rules for proper procedure when its troops intervened to rescue 169 starving and physically abused, mostly Sunni Arab, detainees in an interior ministry-run detention center in the Jadriyah district of Baghdad.

U.S. troops made the discovery on November 13, while visiting the facility to look for a missing Sunni Arab teenager.

It is not yet clear whether the Iraqi government intends to continue with its investigation.

Prime Minister Jaafari has vowed to severely punish anyone found guilty of abusing prisoners. He has been under intense pressure to answer Sunni Arab charges that high-ranking members of the Iraq's interior ministry, which controls the police, are working with an Iranian-backed Shi'ite militia called the Badr Brigade to round up, detain, torture, and kill Sunni Arabs for sectarian reasons.

The Badr Brigade is widely believed to be the armed wing of the Supreme Council of the Islamic Revolution in Iraq, the largest and the most powerful Shi'ite party in government.

Iraq's interior minister, Bayan Jabr, who is a party member and a former Badr Brigade commander, denies that Badr fighters have been integrated into units in his ministry. He has also angrily accused Western and Iraqi media of exaggerating the alleged torture of detainees in Jadriyah and other interior ministry-run facilities.

Saad Juwad Qindeel is a spokesman for the Supreme Council of the Islamic Revolution in Iraq and a member of the Iraqi National Assembly. He suggests that the abuse scandal is being used by Sunni groups to discredit Shi'ite parties and to bolster their political standing among voters in Iraq's crucial national elections on December 15.

"I can identify many media centers who have tried to exaggerate the issue, [tried] to misinform and disinform in explaining what has happened. All political parties have made use of it," he said. "They have played the game of distorting the facts, exaggerating the issues and trying to present the whole issue in a way to win more votes."

The U.S. Embassy in Baghdad has praised Prime Minister Jaafari's promise to investigate the scandal as proof that Iraq's Shi'ite-dominated government was committed to being transparent about its activities.

But Sunni leaders say they do not believe the government will conduct a fair, unbiased inquiry. On Wednesday, they renewed their calls for an international investigation into the matter.