A senior US army officer in Iraq was found guilty on Friday of possessing thousands of secret military documents that the prosecution in his court martial argued could have benefited a foreign power.

Lieutenant-Colonel William Steele, 52, was acquitted on the more serious charge of aiding the enemy, which carried a sentence of life imprisonment, for allowing security detainees to use his mobile telephone for unmonitored calls.

He faces up to 10 years' imprisonment on the secret documents charge. He was also found guilty of having an inappropriate relationship with an Iraqi woman interpreter and refusing to obey an order.