Iraq's Interior Ministry has launched an investigation into claims that a police death squad has been operating in the country, a top official said Thursday. Attacks around the country killed at least 19 people, including six Iraqis in a car bombing and three sheiks in a drive-by shooting.

Iraq Prime Minister Ibrahim al-Jaafari also condemned the latest images of detainees abused in the U.S.-run Abu Ghraib prison in 2003, but noted that those responsible had already been punished.

The investigation into the death squads was announced as police found the bodies of 12 more men who had been shot execution-style and dumped in three different areas of Baghdad's predominantly Shiite suburb of Shula.

Maj. Gen. Hussein Kamal, Iraq's deputy interior minister in charge of domestic intelligence, said the investigation followed U.S. military claims that soldiers had detained 22 Iraqi men wearing police uniforms who were about to kill a Sunni Arab man last month.

"We have been informed about this and the interior minister has formed an investigation committee to learn more about the Sunni person and those 22 men, particularly whether they work for the Interior Ministry or claim to belong to the ministry," Kamal told The Associated Press.

A U.S. general said American forces had found evidence of a death squad operating in Iraq's Interior Ministry, the Chicago Tribune reported on its Web site Wednesday evening. Maj. Gen. Joseph Peterson, who commands the civilian police training teams in Iraq, said the men were employed by the Interior Ministry as highway patrol officers.

An American military official in Baghdad confirmed the report but declined to provide further details. He spoke on condition of anonymity as he was unauthorized to speak to the media.

The bodies of Sunni Arabs, bound and gagged and shot in the head, have been turning up in Baghdad for months, fueling allegations of sectarian killings, which Sunni Arab leaders say are often carried out by Shiites in army or police uniforms.

Shiites have also been systematically massacred by Sunni extremists in Baghdad, Diyala province and mixed areas to the south of the capital.

Human Rights Minister Nermine Othman said she believed lower-level Interior Ministry officials were using criminals to kill Iraqis.

"I think there are many people inside the Interior Ministry involved with these deaths or giving the uniforms of colleagues to criminals," she said. "These officials are helping the criminals by informing them on where targeted people are going or where people are living. They are helping them in different ways."

A Sunni Arab political group, the Iraqi Islamic Party, praised the investigation and said perpetrators should be brought to justice.

"Since a very long time, we have been talking about such violations and we have been telling the Interior Ministry officials that there are squads that raid houses and arrest people who are found later executed in different parts of the capital," said party member Nasser al-Ani.

In the latest violence, a car bomb targeting a U.S. military patrol killed six civilians and wounded 11 Thursday in northern Baghdad's Shula neighborhood, said police Maj. Moussa Abdul Karim.

Three prominent tribal figures driving to a funeral were killed by gunmen spraying machine-gun fire from a minibus in Khan Bani Saad, about 25 miles northeast of Baghdad, Diyala police's Joint Coordination Center said.

Police identified the victims as Sheik Mindab al-Khafaji, 55, a clan leader and head of Khan Bani Saad tribal council; Sheik Hanash al-Moussaoui, 45, a member of Khan Bani Saad's local council; and Raad Ahmed Chibish al-Jibouri, 45, a Sunni Arab member of the tribal council.

"We condemn these criminal acts directed against our brothers," said Abdul-Rassoul Saeed, head of Khan Bani Saad council. "The aim of this attack is to ignite civil strife, but such efforts will fail."

Khan Bani Saad is a predominantly Sunni Arab town of about 40,000 people on the edge of Diyala province, which borders Baghdad. It has been the scene of previous attacks targeting religious leaders and supporters of U.S.-led reconstruction.

In downtown Ramadi, gunmen also killed the brother of the deputy governor of the volatile western Anbar province, police Lt. Khalid al-Dulaimi said.

An Iraqi policeman was killed and three bystanders were wounded by a car bomb in Baghdad's Karradah neighborhood, while gunmen killed an Iraqi Army captain and his driver in the northern city of Kirkuk, police said.

Gunmen killed two more policemen and two civilians — one Iraqi and the other Egyptian — in an attack on a vehicle in west Baghdad's Amariyah district, and another policeman was shot dead in the Amil area, police. A mechanic was gunned down by three gunmen in southern Baghdad's Dora district.

A Jordanian Embassy driver of Iraqi nationality was seriously wounded in a western Baghdad drive-by shooting, said a hospital official.

Another car bomb blast in Baghdad targeted the convoy of Nouri al-Nouri, a former government human rights official who was dismissed in December over the discovery of tortured detainees in a Baghdad government building. Al-Nouri escaped the blast unharmed but four civilians were wounded, police Lt. Mohammed Khayoun said.

The motive for the attack was unclear, but it came as Othman, the human rights minister, said several Interior and Justice Ministry employees were expected to be prosecuted over the torture about 170 Iraqis, most found in November at the Jadriyah Interior Ministry facility in Baghdad.

Othman said her ministry will release a final report on the torture claims next month.

In a statement on the detainee abuse photos broadcast on an Australian TV station Wednesday, al-Jaafari said "the Iraqi government condemns the torture practices revealed through the recent pictures that show Iraqi prisoners being tortured."

But he welcomed the U.S. denunciation of the pictures, which date back to 2003, when earlier images were released of U.S. forces abusing detainees.