Iraqi security forces found 37 badly decomposed bodies in a mass grave north of Baghdad and some showed signs of torture, the US military said.

US forces said it was not clear who was responsible for the grave near Muqdadiyah, 90 km (55 miles) northeast of Baghdad.

"All the bodies were badly decomposed and appear to have been there anywhere from two to eight months," the military said in a statement. "Some of the bodies showed signs of torture."

Tens of thousands of Iraqis have been killed in sectarian fighting between majority Shi'ites and minority Sunni Arabs.

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