Prime Minister Scott Morrison has dismissed fresh claims the federal coalition pressured government scientists to rush through a key approval for the multi-billion dollar Adani coal mining project.
Groundwater plans for the proposed central Queensland mine were approved by federal environment minister Melissa Price on April 8, two days before the May 18 national election was officially called.
In announcing her decision, Ms Price, who has been largely absent from the coalition's national election campaign, said she had acted on "scientific advice".
Queensland is a key battlefield for the coalition, which is fighting to retain government in the face of polls projecting a Labor win.
Now documents obtained by the ABC under Freedom of Information laws imply the Commonwealth decision to approve the water plan was rushed after environment department officials pushed for a result on the afternoon of Friday April 5.
The documents also imply the assessment of the CSIRO cited by Ms Price as approving the plan was not as clear cut as suggested.
But Mr Morrison says CSIRO and Geoscience Australia took part in an earlier review of the plans, later confirming Adani had met requirements before being granted final approval.
"If they don't want to support something, then they won't, and they certainly wouldn't do that in writing if they weren't 100 per cent behind it," he said.
"And they did."
Federal Labor leader Bill Shorten called on Ms Price to explain herself, despite saying an elected Labor government would not review the decision.
The documents obtained by the ABC include an email by a senior CSIRO research director saying the agency was being careful "not to be categoric" in its response because "the devil is in the detail we do not have".
The Australian Conservation Foundation said this showed key CSIRO officials had reservations about Adani's groundwater plans.
"These documents show political pressure was put on CSIRO to quickly back Adani's groundwater plans and provide cover for the rushed approval by the Environment Minister just days before the election," ACF campaigner Christian Slattery said.
The mine's final approval now rests with the Queensland government, which must sign off on plans to manage groundwater and the endangered Black-Throated Finch before construction can start.
It has asked for reviews of the latest version of those plans.
Adani says it has asked to see specific questions the Queensland government has now put to CSIRO and Geoscience Australia, but its request has been refused by the state Environment Department.
Premier Annastacia Palaszczuk denies her government is holding up the project, saying it is going through the same standard of approval as any other mining project.
"It's not just one rule for Adani and one rule for everyone else," she said this week.
But the state's peak resources lobby said that's not the case.
"No one could say with a straight face that the Carmichael coal project has been treated like any other mining project," Queensland Resources Council chief executive Ian Macfarlane said.
Ms Palaszczuk on Tuesday announced Pembroke's $1 billion Olive Downs coal mine project in the Bowen Basin had been granted conditional approval.
