The Queensland Treasury and the Department of Premier and Cabinet were frozen out of key government decisions about the controversial $16 billion Adani Mining project.

Documents obtained by the ABC revealed senior Treasury bureaucrats were even "uninvited" from a high-level meeting involving the company and the Department of State Development.

The Indian giant wants to develop a massive coal deposit in the Galilee Basin in central Queensland.

Hundreds of millions of dollars of Queensland taxpayers' money was earmarked by the former Newman government to facilitate the project on the promise of thousands of jobs.

Galilee Basin statistics The Galilee Basin is 247,000 square kilometres in size.

The Galilee Basin is 247,000 square kilometres in size. The proposed mining projects within the basin have the potential to attract investment of between $3.8 and $4.8 billion and could provide about 1,200 jobs per year.

The proposed mining projects within the basin have the potential to attract investment of between $3.8 and $4.8 billion and could provide about 1,200 jobs per year. Prices of thermal coal have dropped in recent years from a high of nearly $142 ($US per tonne) in early 2011, to about $62.

Prices of thermal coal have dropped in recent years from a high of nearly $142 ($US per tonne) in early 2011, to about $62. Greenpeace estimates if the Galilee Basin mines are developed to their maximum potential, 705 million tonnes of CO2 would be released each year.

The documents outlining the Adani negotiations, obtained under Right to Information laws, reveal confusion and suspicion among high-ranking Queensland bureaucrats about the decision-making process, with the head of Treasury bluntly warning: "I would prefer to keep at arm's length at present, and not get trapped into a set-up".

The documents showed the set-up he feared was not from Adani, but from the Department of State Development under then deputy premier Jeff Seeney.

Mr Seeney's department was driving the negotiations with the Indian company.

Those talks led to draft agreements that were signed without consultation with the Department of Premier and Cabinet or with Treasury.

In one email, a Treasury official complained about how the Department of State Development was handling the drafting of a paper about rail and infrastructure options for the Galilee Basin, saying a colleague in State Development "was most reluctant to give me any detail or the actual paper".

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Investment agreement done without Treasury's knowledge

In November 2014, the Department of State Development signed a series of agreements with Adani, including an infrastructure investment agreement and a statement of intent.

Jeff Seeney's department was driving the negotiations with the Indian company. ( AAP: Dave Hunt, file photo )

The deal meant the Queensland Government was prepared to put in $455 million of taxpayers' money, with critics arguing there was no guarantee the company would repay it.

The agreement was news to Treasury head Mark Gray, who emailed seeking details from his counterpart in the Department of State Development, David Edwards.

"Hi David, I understand from the Treasurer that some document or agreement was signed today with Adani. Would you please be able to send through a copy for our information?," the email read.

The following day, another Treasury official emailed a colleague in the Department of Premier and Cabinet, complaining that, "I suspect that we've missed the train and this will continue to be a [Department of State Development]-only show."

"[The documents make] for bizarre reading," Tim Buckley, the director of Energy Finance Studies Australasia and a critic of the Adani project, told the ABC.

"I mean, the Queensland Treasury, you would think, would be the one doing the due diligence, would be running the numbers, checking that the substance of any transaction makes sense."

Departments 'uninvited' from key meeting

That Treasury and the Department of Premier and Cabinet had been sidelined is confirmed in another internal email, in which Treasury official David Quinn told a colleague: "[I'm] not sure what it all means to be honest".

The freeze-out continued in December 2014, when officials from the departments of Premier, Treasury and State Development were due to meet, first among themselves and then later that day with Adani.

In an email, Mr Gray wrote to his colleague Jason Wishart: "Is [Department of State Development director-general] David Edwards attending this earlier meeting today?

"I would prefer to keep at arm's length at present, and not get trapped into a set-up."

Indian giants Adani wants to develop a massive coal deposit in the Galilee Basin in central Queensland. ( AAP, file photo )

When told that Mr Edwards would be attending, Mr Gray sent another email.

"I assume then that [Mr Edwards] is just wanting to give everyone "riding instructions" for meeting with Adani later today.

"Best to take a low profile in Adani meeting."

Later that morning, Mr Wishart replied to Mr Gray to inform him that: "[Treasury] and [Department of Premier and Cabinet] have been 'uninvited' to the 3:00 meeting with Adani today".

"It appears the Department of State Development went rogue on this particular project and they didn't want to consult with Treasury, they didn't want to consult with Premier and Cabinet. They didn't want advice," the North Queensland Conservation Council's Jeremy Tager said.

Other departmental documents revealed the Queensland Treasury was concerned about Adani's level of debt and the company's capacity to fund the multi-billion-dollar Carmichael mine project, with one bureaucrat warning, "it's unlikely to stack up on a conventional project financial assessment".

In December last year, Mr Gray emailed his deputy, warning: "We need to stay vigilant on this one as I don't have any confidence that [the Department of State Development] will get funding out of Adani or anyone else".

Doubts have been growing about demand in Adani's main target market, India, which recently shifted its focus to domestic coal resources.

The company has also admitted its jobs promise was over-inflated.

The Government said views raised in the documents related to the former LNP government's dealings with Adani, saying Mr Gray was no longer with Queensland Treasury.

State Development Minister Anthony Lynham welcomed Adani's investment proposal and expected the company to meet all of its obligations in relation to all State and Commonwealth legislation.

"We will meet all our election commitments on this project, both in terms of the dredging project at Abbot Point and [by] not making direct government contributions towards funding the railway," he said.