Iraq's prime minister disclosed Tuesday that more than 170 malnourished Iraqi detainees were found at an Interior Ministry detention center and that they appear to have been tortured.

A leading Sunni politician said the inmates were Sunni Arabs and the Shiite-led government had long ignored complaints of abuse there.

The announcement came two days after U.S. troops surrounded and took control of an Interior Ministry building in the Baghdad neighborhood where the detainees were found, although the Iraqi leader didn't say whether American forces were involved in discovering the center.

Amnesty International welcomed al-Jaafari's decision to order an investigation but urged him to expand the probe to include all allegations of torture. Amnesty also asked him to make the results public.

"I was informed that there were 173 detainees held at an Interior Ministry prison and they appear to be malnourished. There is also some talk that they were subjected to some kind of torture," Prime Minister Ibrahim al-Jaafari told reporters.

Al-Jaafari said the detainees were moved into a better location and "medical care will be given to them."

An Iraqi Interior Ministry official also said Monday that an investigation will be opened into allegations that ministry officers tortured suspects detained in connection with the country's insurgency.

But the head of the country's largest Sunni political party said he had personally spoken to al-Jaafari and other government officials about torture at Interior Ministry detention centers, including the one where the detainees were found.

But, he said, the government routinely dismissed his complaints, calling the prisoners "former regime elements."

"According to our knowledge, regrettably, all the detainees were Sunnis," Mohsen Abdul-Hamid, head of the Iraqi Islamic Party, told The Associated Press. "In order to search for a terrorist, they used to detain hundreds of innocent people and torture them brutally."

Most insurgents are Sunni Arabs, who were dominant under Saddam Hussein's regime but lost power after his ouster.

The Interior Ministry is controlled by Shiites. Sunni leaders have accused Shiite-dominated security forces of detaining, torturing and killing hundreds of Sunnis simply because of their religious affiliation.

The prime minister did not say where the prison was located, but Maj. Gen. Hussein Kamal, the Interior Ministry's undersecretary for security, said it was in the basement of a building in Baghdad's neighborhood of Jadriyah.

Amnesty International also said it had recently received information of four people who were tortured while detained by Iraqi security forces.

"There have been many reports of torture and maltreatment of Iraqi detainees by the Iraqi police and security forces belonging to the Ministry of Interior such as the Wolf Brigade," spokeswoman Nicole Choueiry said.

In Geneva, the international Red Cross said it was unaware of the detention center but wanted to learn more.

Late Sunday, U.S. troops surrounded and took control of an Interior Ministry building in Jadriyah following repeated allegations that Iraq security forces were illegally detaining and torturing people suspected of participating in the insurgency.

The U.S. military declined comment on the incident and referred all questions to the Iraqi Interior Ministry.

U.S. officials have been encouraging Sunni Arabs to take part in next month's parliamentary elections in hopes that a strong turnout by the disaffected minority could help ease sectarian tensions, calm the insurgency and speed the day when foreign troops could go home.

Al-Jaafari did not say whether U.S. troops were involved in discovering the center.

Al-Jaafari, who is a Shiite, said one of his deputies will be heading a committee that will include some ministers and will investigate what happened. The committee will finish its work within two weeks, al-Jaafari said.

"They should investigate how this happened and how it reached this point," al-Jaafari said.

Kamal said the committee will be headed by Kurdish Deputy Prime Minister Rowsch Nouri Shaways.