Two former Liberal prime ministers have outright rejected a treaty with Indigenous Australians, as public debate continues about the merits of holding a referendum to acknowledge Aboriginal and Torres Strait Islander people.

Key points: Talk of treaty "appalling", John Howard says

Talk of treaty "appalling", John Howard says "Treaty is something two nations make with each other," Tony Abbott says

"Treaty is something two nations make with each other," Tony Abbott says Real issue is the scope of referendum question, Mr Howard says

John Howard has described talk of a treaty as "appalling", and Tony Abbott says he has never supported the idea.

The comments come ahead of a new report on consultations about the referendum question.

The interim document has been prepared by the Referendum Council — a group of Indigenous and non-Indigenous representatives, and is expected to be handed to the major parties this week.

Changes to the constitution could include an acknowledgement that Aboriginal and Torres Strait Islander people were the first Australians.

There is a further option to strip the constitution of any racially discriminatory references.

A more controversial proposal includes adding a fresh prohibition against race discrimination in the document.

Given Prime Minister Malcolm Turnbull is still overseas attending international summits, he is unlikely to consider the document until his return on the weekend.

The Referendum Council has acknowledged a building campaign for the Government to consider the report, or a series of treaties, alongside or instead of the referendum.

The Opposition is open to the idea of concurrent consultations on a treaty, potentially along the lines of agreements struck between Indigenous peoples and governments in New Zealand and Canada.

Treaty would split nation: Abbott

Tony Abbott with Clontarf foundation footballers during his current trip to Kununurra in WA ( ABC News: Eliza Borrello )

But former prime minister — now backbench MP — Mr Abbott said he was not in favour of a treaty.

"I never have been," he told AM.

"A treaty is something that two nations make with each other, and obviously Aboriginal people are the first Australians, but in the end we're all Australians together, so I don't support a treaty."

Mr Abbott, who previously proclaimed himself a prime minister for Indigenous Affairs, is continuing with his yearly visits to Indigenous Australia, visiting Kununurra this week.

Mr Howard was also questioned about the treaty push during an address at the National Press Club on Wednesday.

"I'm appalled at talk about treaty, that will be so divisive and will fail," Mr Howard said.

"The Australian public will not be attracted to the idea of a country trying to make a treaty with itself. I think we overcomplicate these things."

Mr Howard said the real issue at stake was the scope of the referendum question.

"I have said publicly as far back as 2007, I would support a change that recognises an historical truth that Aboriginal and Torres Strait Islander people were here before anybody else and that's a historical truth. Nobody can argue with that," he said.

"But once it goes beyond that I think you open up all sorts of other things."

John Howard during his speech to the National Press Club on Wednesday ( ABC News: Marco Catalano )

Backbenchers against holding referendum

Both former prime ministers were central to the successful campaign to sink the last referendum on whether Australia should become a republic.

The failed campaign to ditch formal ties to the monarchy was led by Mr Turnbull.

Mr Abbott had previously been in favour of holding the referendum in May next year, but the lack of consensus on a particular question for voters to consider has blown out the timeframe and means a vote may be put off to 2018.

A group of government backbenchers are agitating against holding a referendum at all, arguing it is not a priority.

Mr Abbott had committed to hold the national vote but it has never been formally endorsed by the Coalition party room.

Human Services Minister Alan Tudge said a treaty was a risky suggestion that would detract from the push for constitutional recognition.

"My fear is that if you add treaty into the mix, you won't get that broad consensus," he said.

"I also have the question about what actually does treaty mean in any case and that's been ill-defined to date as well."

Have a bex and a sit down: Shorten

Opposition Leader Bill Shorten said Labor's priority was a successful referendum but that he was "willing to listen" to those advocating for a treaty or multiple treaties.

"I know there's some people who, if they hear the word treaty, run screaming for the hills," Mr Shorten said.

"I just say to them calm down. Have a Bex and a sit down it will be alright, our First Australians have put up with a lot from the rest of us for the last 225 years plus.

"I think it's appropriate we get recognition in our constitution and we should also talk about the other issues which go to a real settlement with First Australians."