Lawyers for Ben Roberts-Smith have admitted the war hero punched a junior trooper in the face in front of colleagues after a mission in Afghanistan.

The admission on Thursday comes during a defamation trial where Mr Roberts-Smith is suing The Age, The Sydney Morning Herald and The Canberra Times over reports claiming he committed war crimes and bullied colleagues.

A new SAS witness – codenamed Person 10 – told the Federal Court he had been confronted by Mr Roberts-Smith after mistakenly firing in the direction of a woman and child on a mission.

One of his comrades was fired upon moments earlier, and Person 10 thought he saw what he perceived to be a person armed with a machine gun, so started shooting in their direction until Mr Roberts-Smith – his patrol commander – called out for him to stop.

In front of colleagues back at the base, Mr Roberts-Smith ordered Person 10 to stand up, then punched him in the jaw.

“It forced me back … it rattled me. I … did not expect to be punched,” he said.

Person 10 says the Victoria Cross recipient then began “verbally abusing” him, and that the incident could be considered bullying.

Barrister Arthur Moses suggested to Person 10 that his client had only punched him after he giggled when Mr Roberts-Smith questioned him about the event.

“That did not happen,” Person 10 replied.

Mr Roberts-Smith was angry the incident had almost killed a woman and child, Mr Moses said.

He had made an error that that could have resulted in the death of innocent Afghans, Mr Moses said.

“Based off the information I had … I made the decision to fire and I think it is the right one,” Person 10 replied.

“You have to put it into context.”

Person 10 was soon formally debriefed about the incident and accused of firing at his own colleagues, something he says is “simply false”.

“The fact is … you were just spraying bullets … because you panicked,” Mr Moses said to Person 10.

He denied that, and said he later learned it was actually he and his partner that had been fired upon by another SAS patrol – the initial shots that sparked the incident.

The newspapers Mr Roberts-Smith is suing for defamation allege the accusation against Person 10 was invented to distract from the fact the mission the decorated war hero had planned was a failure and nearly fatal.

Based on what he heard from his colleagues, Person 10 told the court he also formed the view that he had been made a “scapegoat” for the mission’s failure.

Person 10 was soon moved to another patrol, where he slumped into a depression and his performance in the defence force plummeted.

As he faced the prospect of being removed from the regiment at the end of his deployment, Person 10 told the court he received an intimidating phone call from Mr Roberts-Smith.

“The crux of it was … if you threaten me or my family I will f*** you up.”

“My understanding was that if I stated that he punched me … there would be consequences.”

He earlier told the court Mr Roberts-Smith had also ordered him to mock execute a colleague pretending to be an Afghan prisoner – bound and on his knees – at a pre-deployment training exercise.

“He said, ‘That’s how it’s going to be on the day’,” Person 10 said.

Mr Moses put to him that he had lied about his evidence because he was embarrassed about his performance in the army, and blamed Mr Roberts-Smith for the demise of his career.

“You have difficulty accepting responsibility when something bad happens … when you do the wrong thing,” Mr Moses said.

But Person 10 said he owned up to his mistakes and poor performance, saying it was “nobody else’s fault but mine”.

“I hold nothing against Mr Roberts-Smith,” he said.

The trial continues.