Former corporal Donald Payne told the public inquiry into Mousa’s death that he witnessed Lieutenant Craig Rodgers punching or kicking a group of detainees and even pretending to set one of them alight.
Payne also claimed Lieut Col Jorge Mendonca, commanding officer of the former 1st Battalion Queen’s Lancashire Regiment (1QLR) in Iraq in 2003, was “gung ho” and “trigger happy”.
Mousa, 26, died in Basra, southern Iraq, on September 15, 2003, while in the custody of the 1QLR, having suffered 93 separate injuries.
Payne became the first member of the British armed forces to be convicted of a war crime when he pleaded guilty at a court martial to inhumanely treating civilians.
Giving evidence to the public inquiry in central London yesterday, he dramatically changed his account to admit for the first time that he used “gratuitous violence” against the detainees and witnessed other soldiers copying him.
Payne told the inquiry he had until now covered up the extent of the abuse of Mousa and other Iraqis arrested with him out of “misguided loyalty”. He claimed he saw every member of the unit commanded by Lieut Rodgers, known by the call sign G10A, beating the prisoners.
The disgraced non-commissioned officer said in a statement: “I now disclose that in adopting the routine I did each time I returned to the temporary detention facility to ensure the detainees were awake, the degree of force I applied was greater than I have so far admitted.
“Moreover, at one time or another I saw all the members of the multiple in call sign G10A emulate me.
“I have seen each one, including Lieut Rodgers, forcefully kick and/or punch the detainees in the period between September 14 and 16, 2003. Further, during the morning of Monday, September 15, I observed Lieut Rodgers place a jerry can of petrol in front of the young boy. He poured water over him and then lit a match.”
Rodgers, who left the Army in March 2007 having reached the rank of captain, strongly denied allegations of prisoner abuse when he gave evidence to the inquiry last week. He said in a witness statement: “I did not hit, punch, kick or physically assault any of the detainees at any time.”
Payne admitted that he lied in interviews, to the court martial and in his first statement to the public inquiry for reasons of “self-preservation”. He previously claimed he only nudged or slapped the Iraqi detainees and never saw them being beaten by their guards.
The former soldier suggested that he abused the detainees because he believed, wrongly, that they were linked to the deaths of three members of the Royal Military Police (RMP) in Iraq in August 2003.
The inquiry has been told that British soldiers in Iraq used “conditioning” methods – such as hooding, sleep deprivation and making suspects stand in painful stress positions – banned by Britain in 1972.
The inquiry continues.