A senior Australian army officer says he accepts directions designed to protect soldiers in Afghanistan weren’t followed when three diggers were killed.

The former head of an Australian army mentoring task force says he accepts that a key order designed to protect his soldiers wasn’t passed on before three were killed in an insider attack.

Colonel Trent Scott, who led a battalion tasked with mentoring Afghan National Army forces in Afghanistan in 2012, has told an inquest that the order ramping up security – and which he signed off on – should have been communicated across the task group.

However Col Scott told the Brisbane inquest into the deaths of three soldiers that he couldn’t say he was surprised because there was a lot happening at the time.

Lance Corporal Stjepan Milosevic, Sapper James Martin and Private Robert Poate were gunned down by a rogue Afghan National Army soldier in a so-called green on blue attack at a patrol base in Oruzgan province in August 2012.

An inquest into their deaths has already heard an Australian army order requiring tighter security for interactions with Afghan National Army personnel wasn’t passed on to the dead soldiers’ commander on the ground.

The order specifying guards provide close personal protection to Australian soldiers in “buddy teams” was issued about two weeks before the deadly attack at patrol base Wahab, 20km north of Tarin Kowt.

Col Scott told the inquest on Wednesday that the order was issued as the Australians became more mindful of the threat from insider attacks, which had dramatically increased in the preceding months.

Asked by counsel assisting the coroner Peter De Waard whether it surprised him that Captain Dominic Lopez, the dead soliders’ platoon commander wasn’t aware of the directive, Col Scott replied: “I could accept the fact that that wasn’t passed on.

“Surprise is not the right word. There’s a lot happening over there and they’re doing a lot of work.”

Col Scott also said there was no conflict of interest in the dead soldiers’ unit commander Major Travis Gordon conducting the initial investigation into the attack by an Afghan National Army sergeant with links to the Taliban.

He said the “quick assessment” was designed to establish the facts and that he had “full confidence” in his entire team on the ground.

“We were managing a very volatile, extremely lethal situation and only through the strong leadership of the folk there did it not deteriorate into sometime worse,” Col Scott told the court.

The inquest continues on Thursday.