Australia’s premier scientific research agency is distancing itself from the federal government’s decision to give final federal environmental approval for the Adani Group’s Carmichael coalmine in central Queensland.

The Commonwealth Scientific and Industrial Research Organisation, whose advice was cited alongside that of Geoscience Australia as the basis for the decision, says it was only responsible for answering a narrow set of questions, not giving the project’s whole groundwater plan a tick of approval.

The CSIRO has revealed that the undertaking Adani gave to improve its plans, which preceded federal government approval, allows it to take up to two years to redesign and check its modelling.

Two days before Prime Minister Scott Morrison named May 18 as polling day, Environment Minister Melissa Price approved the groundwater management plans for the Indian-owned Adani Group’s controversial mine.

That approval removed the last federal hurdle Adani needed to clear before its mine in central Queensland’s as-yet-untapped Galilee Basin could go ahead. Two more approvals are still required from the Queensland government.

Labor and the Greens have accused Price and the Coalition government of rushing the approval under pressure from Queensland Liberal National MPs, who want the coalmine to proceed and agitated privately and increasingly publicly last week to have it endorsed before the election was called.

CSIRO’s executive director for environment, energy and water, Dr Peter Mayfield, told The Saturday Paper that his agency and Geoscience Australia wrote two reports for the government addressing “specific questions on groundwater monitoring, management and modelling” related to plans that Adani had prepared for its central Queensland mine proposal.

“This advice was limited to answering discrete inquiries on whether elements of Adani’s proposed plans would be adequate to protect nationally significant environmental assets,” Mayfield said.

In that advice, CSIRO had found a number of problems with Adani’s proposed groundwater plans and recommended changes. The environment department, which has the role of regulator, summarised and conveyed those concerns to Adani, which then undertook to make adjustments.

“Adani had committed to address the modelling limitations identified by the CSIRO and Geoscience Australia review in a groundwater model rerun to be undertaken within two years,” Mayfield said. “CSIRO considered that this commitment satisfied our recommendations, whilst also acknowledging that there are still some issues that need to be addressed in future approvals, particularly confirming the source of the ecologically important Doongmabulla Springs.”

Mayfield emphasised that CSIRO provided “robust, peer-reviewed science on specific groundwater modelling-related questions about the plans”.

“CSIRO’s role is to provide scientific advice to inform approval processes, but it does not have any role in making approval decisions,” he said.

The original advice, jointly presented by CSIRO and Geoscience Australia, was dated February 22 this year. Departmental officials told an estimates committee on Monday that after further consultation, Adani had provided revised plans on March 15.

The minister requested and received the agencies’ advice on Monday April 1, the day before parliament resumed.

“The federal minister’s decision … reeks of political interference and in many ways puts into question the integrity of her decision-making process.”

It is understood the Queensland LNP senator Matt Canavan, the minister for resources and Northern Australia, went to see Morrison on Thursday last week, demanding the approval be granted. Canavan has denied media reports that he threatened to quit the ministry if the prime minister did not oblige.

A group of Nationals, including former deputy prime minister Barnaby Joyce, are understood to have met separately to discuss how to expedite a decision.

Adani’s chief executive in Australia, Lucas Dow, was in Canberra the same day, also lobbying for the approval.

The next day, Price’s department conducted what officials described as “verbal briefings” for CSIRO and Geoscience Australia by telephone, also providing them with a written summary of Adani’s undertakings in response to their concerns but not the full revised plans.

The agencies were not provided with copies of the plans until several days later, after both had made their responses to the department.

Provided later on Friday in the form of short letters to the department, the agencies’ responses formed the basis for Price’s decision.

The letter from Geoscience Australia said Adani had addressed the “issues and concerns” it raised in its recommendations.

But the CSIRO letter contained caveats.

It emphasised that CSIRO’s examination of Adani’s actions was based only on the verbal briefing and the summary information the department had provided.

It said Adani’s responses “should” satisfy the CSIRO recommendations to update the groundwater modelling. But it warned that “there are still components of that advice that will need to be addressed”. Those components would be dealt with through the approval of separate research plans, not required until after the company has broken ground.

On Monday this week, the Queensland LNP senator James McGrath, who sits with the Liberals in federal parliament, was reported as having written to Price, threatening to call publicly for her resignation if she did not give the approval quickly.

She approved the groundwater plans the next day.

The groundwater approvals are the ninth and 10th the federal government has granted to Adani since then environment minister Greg Hunt – who is now the health minister – gave the preliminary green light to the Indian mining giant in 2015.

It was a delegate of the minister – a departmental official – who signed off on the first eight but Minister Price approved the most recent two, the groundwater plans, personally.

Environment groups are now raising the prospect of legal action to challenge the approval, citing undue pressure.

Respected hydrologist and Australian National University adjunct professor John Williams is questioning how the identified problems could have been rectified so swiftly.

“You just can’t go from having concerns to having none through some management options,” Williams says. “… For the reputation of CSIRO and Geoscience Australia, you’d want to have a transparent response.”

Melissa Price announced her decision by media release on Tuesday morning, saying CSIRO and Geoscience Australia had “confirmed the revised plans meet strict scientific requirements”.

The Queensland government must still sign off on the groundwater plans and on Adani’s separate plan for managing the impact on the habitat of the black-throated finch.

Adani’s Lucas Dow welcomed the federal decision and accused the Queensland government of “shifting the goalposts” – a message repeated in advertising material being letterboxed in north Queensland.

Price’s statement said the mine had been through “the most rigorous process” of any in Australia and that the two agencies had provided “written assurances” that Adani had addressed their concerns.

She said among the company’s agreed changes was a substantial increase in early warning monitoring of Doongmabulla Springs – the same springs CSIRO subsequently says it still has concerns about.

Price also said the two agencies’ original advice had been provided to the Queensland government to assist its decision.

The day before the announcement, the environment department’s deputy secretary, Dean Knudson, told the senate estimates committee that it was “essential that advice go to the Queensland government” because “they require that information for their decision-making”.

On Wednesday, Queensland’s environment minister, Leeanne Enoch, revealed the state government received the CSIRO and Geoscience Australia advice just half an hour before it was made public.

The Saturday Paper has been told the advice arrived in Brisbane by email at 10.51am. An updated version of Adani’s groundwater management plan arrived at 11.08am.

Melissa Price issued her media release, containing a web link to the advice, at 11.18am.

“The federal minister’s decision … reeks of political interference and in many ways puts into question the integrity of her decision-making process,” Enoch told journalists.

Enoch said the state government had been asking for the advice for more than a month.

The Australian Conservation Foundation had also sought it, but a March 5 freedom of information request to the federal department was refused on the grounds that releasing it “may have an adverse impact on the ongoing flow of information between the Commonwealth and Queensland government”.

Price’s Tuesday decision won applause from the Carmichael mine’s supporters in the Queensland LNP.

A strong clue to the government’s pre-election haste may lie in the status of three vulnerable Nationals-held seats in central Queensland.

The member for Capricornia, Michelle Landry, and colleagues George Christensen, in Dawson, and Ken O’Dowd, in Flynn, are among those who pushed for the Adani approval.

On the eve of Thursday’s election announcement, the national betting markets had all three seats falling to Labor.

The betting agencies’ odds have historically proved a reasonable guide to the status of seats across the country, on the basis that punters’ actions in parting with their own money carry more weight than their answers to pollsters’ questions.

Former federal bureaucrat and Liberal campaign worker Terry Barnes told Sky News that when he worked in Liberal campaign headquarters, “the most reliable indicator of how we were going were the bookies’ markets”.

The odds will shift during an election campaign, but ahead of Morrison’s election announcement, they showed the Coalition headed for a devastating defeat.

Michelle Landry welcomed Melissa Price’s decision.

“Last week we obviously had a few meetings to discuss this because the Adani Carmichael mine is very important to my electorate and to central Queensland,” Landry told Sky News.

“They said they just wanted to do a few more checks, give them a couple of days, so that’s what we’ve done.”

She said her main opposing candidate in Capricornia was a coalminer, so it was “important that it was signed off by the Coalition”.

CSIRO executives had been due to face questions about their advice and the government’s handling of it at a senate estimates committee hearing on Thursday night, with departmental officials due to appear on Friday.

But instead of making the traditional weekend election announcement, Morrison visited the governor-general before 7am on Thursday and had the parliament prorogued at 8.29am, half an hour before the estimates hearings were due to begin.

Opposition Leader Bill Shorten was suspicious that the election had been called on the day CSIRO was to be questioned about its Adani advice.

“What a coincidence,” Shorten said. “The government, rather than face the scrutiny of parliament about the fairly politicised and bullying process of mine approvals, has instead decided that today they want to have the election.”

Shorten has declined to say if an incoming Labor government would overturn the approvals, saying it would depend how far advanced the process was. He has said previously that Labor would not do anything to create sovereign risk in Australia as an investment destination. He, too, faces internal party pressure both for and against the mine.

Morrison defended Price’s processes.

“I know that the environment minister has conducted herself in the way you’d expect her to do, go through, follow the process to the letter,” he said.

Greens leader Richard Di Natale is condemning both major parties’ handling of the Adani mine and climate change.

“The Labor Party are dragging their heels on climate change but the Liberal Party are dragging their knuckles,” Di Natale said.

Any further questions Labor, Greens or independent senators might have had of CSIRO and the Department of Environment and Energy will be neither asked nor answered.

Not before the election, anyway.