A British sergeant has been accused of firing bullets into the "twitching bodies" of Iraqi militants after the Battle of Danny Boy when 100 Mahdi Army insurgents ambushed a military patrol.

The "very angry" sergeant is said to have fired a full magazine into two rebels who were still alive and into the corpses of gunmen in a ditch, an inquiry in London was told.

Former army private Duncan Aston was giving evidence at the Al-Sweady Inquiry, which was set up in 2010 to look into the alleged unlawful killing of Iraqi rebels who were captured by British troops and held at Camp Abu Naji and Shaibah Logistics Base in 2004 after the Battle of Danny Boy, named after a British army checkpoint. Twenty Iraqi men died.

The claims that the detainees were mistreated and killed have been denied by the Ministry of Defence.

Up to 200 military witnesses are expected to appear. The first, Col Adam Griffiths, said that claims that soldiers mutilated dead Iraqis after the battle were "baseless rumours".

However, Aston said he saw mistreatment after he was sent to the area in the aftermath of the battle.

While collecting weapons from victims, he noticed two men twitching and said they appeared "somewhere between life and death" but beyond the help of medical attention.

He then saw Paul Kelly, his platoon sergeant, looking "very angry".

"He then threw his rifle to the ground and said words to the effect of 'give me your weapon'.

Stopped twitching

"He put a full magazine of bullets into both bodies that had been twitching but he also fired into the bodies of the other dead gunmen in the ditch.

"The bodies of the two twitching gunmen stopped twitching - there was no other reaction from the bodies. They did not make any other noise, they just stopped twitching."

In another incident, Aston said that a private had stamped on the head of a dead body while screaming and shouting.

Aston also saw two privates hitting and kicking a detainee in the face, shins and ribs.

"Everyone was a bit upset about the whole scenario of British soldiers being ambushed and attacked when we felt we were in Iraq to assist," he said.

"There was no real aggression or wanting to physically seriously hurt him [the detainee]. It was more intimidation and bullying rather than wanting to cause him any serious harm."

Aston said he had not reported the incidents because he did not want to "grass" on his colleagues. He said he spoke to another private who saw the twitching body incident and they agreed not to tell the Royal Military Police

"[We thought] Sgt Kelly might find out and cause problems for us in the army in some way," he said.