The Afghan sergeant who killed three Australian soldiers in a rogue attack is still challenging the severity of his sentence, a court has heard.

A rogue Afghan army soldier who killed three Australian diggers has lost an appeal against his death sentence, but could still be saved by his country’s legal system.

The news emerged during a pre-inquest hearing in Brisbane over the 2012 deaths of Lance Corporal Stjepan Milosevic, Sapper James Martin and Private Robert Poate in Afghanistan.

The soldiers, all from Queensland, were killed in a so-called green on blue attack, when an Afghan National Army sergeant, named Hekmatullah, opened fire in August 2012 with an automatic weapon.

Two other diggers were wounded in the attack, which occurred inside a patrol base 20km north of Tarin Kowt in Oruzgan province.

Counsel assisting the state coroner, Peter De Waard, told the court Hekmatullah’s appeal, heard last month, upheld an original Afghan court decision he be sentenced to death.

There was no question the rogue soldier caused the deaths, given he had admitted to the shooting, but he had appealed against the severity of his sentence, Mr De Waard said.

The matter was still to be considered by Afghanistan’s Supreme Court, which “could take some time”, he said.

The Department of Foreign Affairs and Trade (DFAT) was not confident all legal avenues to the appeal had been exhausted.

“They (DFAT) indicated that they are wary and increasingly concerned about the lack of precision and detail in the information they are able to source from Afghanistan,” Mr De Waard said.

“They are not in a position to say confidently that the initial appeal is no longer an issue for consideration or review in the Afghanistan appellant system.”

Private Poate’s parents heard the news from the public gallery.

The inquest, held at the request of the diggers’ families, will examine the adequacy of Australian Defence Force risk-mitigation plans to prevent insider attacks and offer recommendations.

Eleven Defence witnesses, including squadron leaders and intelligence officers, will be called to give evidence.

Mr De Waard said a key challenge during the inquest would be determining what evidence should be omitted from hearings on the basis of national security.

Queensland’s deputy coroner, John Lock, said the inquest would be held for a week from June 30, unless another pre-trial hearing was needed on June 6.