Ten US servicemen have been killed over the past two days in Iraq, including five marines killed in a gun battle in the country's western Anbar province.

The marines "were killed in action during a fire fight" on Wednesday in the town of New Ubaydi, near the border with Syria, a US military statement said.

"During the engagement, 16 enemy fighters were confirmed killed," it added.

Earlier the US military announced that three US soldiers "were killed when their patrol struck an improvised explosive device northwest of Baghdad" on Tuesday.

Another Marine was killed on Tuesday "by a suicide vehicle-borne improvised explosive device attack (car bomb) while conducting combat operations against the enemy", the military said.

The marine was killed near the town of Al-Karmah, just outside the restive Sunni Arab city of Falluja, west of Baghdad.

The US military announced on Thursday that another soldier had died of wounds sustained in a roadside bomb explosion in northwest Baghdad.

The soldier, who was not immediately identified, was wounded on Tuesday and died on Wednesday.

Prisoner abuse scandal erupts

Meanwhile in Baghdad, the Sunni-based Islamic Party called for an international inquiry following revelations that some 170 detainees, mostly Sunni, were illegally held at an interior ministry complex in south Baghdad.

US forces raided the Jadariyah facility, controlled by the Shiite-dominated ministry, on Sunday.

The commander of US-led forces in Baghdad vowed to inspect all Iraqi detention facilities after the alleged abuse emerged.

US forces stumbled on the secret prison after a Sunni family reported that their 15 year-old son had been arrested and was believed to be held at Jadariyah, a senior US officer said Wednesday.

The Islamic Party called on Shiite Grand Ayatollah Ali Sistani, the premier figure of Shiite Islam in Iraq, to publicly denounce the scandal, with party spokesman Ayad Samarrai saying past abuse allegations have "led to nothing".

US Ambassador Zalmay Khalilzad and General George Casey, the head of the US-led military coalition in Iraq, said that detainee mistreatment was "totally unacceptable."

Iraqi deputy interior minister Hussein Kamal told CNN television that he saw "signs of physical abuse by brutal beating. One or two detainees were paralyzed. And some had their skin peeled off various parts of their body."

CNN also showed a film given to them by the deputy governor of Diyala province, just northeast of Baghdad, showing evidence of alleged abuse of prisoners at the hands of police and dating from August.

The footage showed a group of three or four men, each with handcuffs dangling from one hand, with severe bruising over their backs, shoulders and thighs, along with lacerations apparently caused by beatings.

The Committee of Muslim Scholars, Iraq's main Sunni religious organisation, accused interior ministry services of resorting to torture and ransoming prisoners.

Committee spokesman Sheikh Abdel Salam al-Kubaissi said his organisation had "filmed testimony of released detainees who had been tortured," and that the videos were handed over to Arab League chief Amr Mussa when he visited Baghdad last month.

The sheikh also accused "interior ministry services of detaining people at night in their homes on terrorist charges and then torturing them into making confessions, parts of which are then broadcast on television".

Some detainees were released a month or two later "after paying a bribe, with no charges being brought against them," Kubaissi added.

PHOTO CAPTION

An Iraqi man kneels blindfolded between US Marines after being detained at a snap checkpoint set up moments earlier in Zaidon, located southeast of Fallujah, during a US Marine operation. (AFP)