Home Affairs Minister Peter Dutton said given the gravity of the allegations, it was appropriate that a special investigator assess each case forensically.

"That will take, I think, a longer period of time than people probably expect," he told the Nine Network on Friday.

"But it needs to be gone through thoroughly and we owe that to the soldiers, but we need to take the allegations very seriously."

Labor defence spokesman Richard Marles said the government was right to hold Australian Defence Force members to account.

"It's going to be difficult but it's a really important process, and ultimately it does say a lot about our country that we are willing to do this to ourselves," Mr Marles said.

The Morrison government has set up a special investigator's office to examine the findings of a report by Major General Paul Brereton - who is also a NSW Supreme Court judge - into rumours and allegations dating from 2005 to 2016.

A panel of experts will also oversee the ADF's broader response.

A public version of the Brereton report will be released next week, which Prime Minister Scott Morrison warned will contain "difficult and hard news".

Veterans' Affairs Minister Darren Chester said a "relatively small number of people" had questions to answer about serious allegations.

"It's important we maintain our confidence and our pride and our respect for the men and women in uniform who keep us safe," he told Sky News.

Mr Chester said the process would take at least a couple of years.

Sources said the report was not expected to contain names of soldiers, alleged victims and witnesses but the fine detail of incidents will be revealed.

The office of the special investigator will look at criminal matters raised in the report, gather evidence and potentially refer briefs to the Commonwealth Director of Public Prosecutions.

It will be led by either a senior counsel or retired judge with experience in international law.

The office will be staffed with investigators from the Australian Federal Police, state police experts and legal counsel.

The Brereton inquiry examined 55 separate issues and called 338 witnesses, mainly related to alleged cases of unlawful killings and cruel treatment.

In March, the ABC aired footage from a helmet camera showing an Australian soldier shooting dead an apparently unarmed Afghan man in a field in May 2012.

A former SAS soldier has also told the broadcaster he saw three incidents of alleged murder.

A range of similar allegations has been levelled at special forces.

Australia Defence Association director Neil James said some of the investigations could take a decade, but the nation needed to face up to the issues and fix them.

"Everybody in the defence force wants an adequate resolution of what until now has been a rumour mill," he said.

"The greatest way of stopping that is to have your day in court and be found guilty or not guilty by a judicial process."

Mr James understands some of the allegations relate to "people that previously the country has held in high regard".

Australian Associated Press