The witness codenamed Person 43 who was medically discharged from the special forces in 2017 gave evidence in the Federal Court on Thursday about an April 2009 mission dubbed Whiskey 108 in Uruzgan province.

The sergeant at the time had gathered with other patrol commanders for a briefing when he saw another soldier codenamed Person 35 kick over grass or hay while exploring the Taliban compound.

"I noticed immediately he had spotted something," he said, adding that Person 35's weapon was then pointed down at a tunnel entrance.

He ran over to provide assistance and cover while calling for an interpreter to warn whoever was inside to come out, he said.

"Before the interpreter had reached us, someone appeared crawling out of the tunnel."

In about 10 to 15 seconds the bearded elderly Afghan man appeared dressed in light traditional clothing, he said.

Person 35 said he reached down and grabbed him, along with "several other pairs of hands".

'We PUC'd that person straight away," he said, referring to placing a person under control by way of searching their clothing for weapons and loose items, before they are "handcuffed and possibly blindfolded".

The prisoner was then handed on to other teammates and he never saw him again, he said.

While his troop were leaving the area another soldier dubbed Person 40 asked "where were the PUCs?".

"I answered, something along the lines of, 'you know where they are'.

"I left it up in the air, a bit of a vague comment, meant to not incriminate someone for something I didn't know had happened or not happened."

Person 40 appeared upset, and "basically said 'that's f***ed'".

The media outlets Mr Roberts-Smith is suing for defamation accuse him of throwing one of two prisoners found in the tunnel on the ground and executing him.

The 43-year-old denies the allegation and is suing The Age, The Sydney Morning Herald and The Canberra Times over reports that he committed war crimes and murders in Afghanistan between 2006 and 2012.

He previously told the court "there were no men in the tunnel".

Person 40 finished giving evidence on Thursday about the same incident, and said two prisoners including one with a prosthetic leg quickly surrendered and emerged from that tunnel.

He allegedly watched Mr Roberts-Smith then march the men away where he believed they would be tactically questioned before taken back to Australia's military base.

Person 40 later walked past the body of the man with the prosthetic leg, and said he later suspected it was Mr Roberts-Smith who "pulled the trigger," following comments from squadmates.

Arthur Moses SC on behalf of Mr Roberts-Smith asked the witness if "rumours run rife in the unit?"

"They do sometimes."

"You never saw two persons coming out of the tunnel," Mr Moses said.

"Absolute nonsense and I completely disagree," Person 40 said.

Both witnesses confirmed no prisoners were taken back from that mission to the Australian base camp at Tarin Kowt.

The trial continues.

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