Former prime minister Malcolm Turnbull has been asked to front the Senate inquiry into his government's controversial $443 million grant to the Great Barrier Reef Foundation early next year.
The request comes as state and federal environment ministers meeting in Canberra on Friday failed to agree on the wording over climate action, and a separate report identified a heavy environmental toll if the Galilee Basin coal mines including Adani's proposed Carmichael project proceed.
Mr Turnbull has been offered any dates "that would be appropriate between now and early February", and at "your preferred location" for a public hearing into the controversial grant to the non-profit organisation announced last April.
The former prime minister's attendance is voluntary and it is understood he is the final witness the committee wants to interview. The inquiry has also won an extension to provide its final report by February 13.
The grant surprised even the foundation, which at that point had just six full-time employees. It also bypassed established government agencies such as the CSIRO and the Australian Institute of Marine Science.
Meanwhile at a meeting of environment ministers in Canberra, the Labor-led state and territory ministers criticised Melissa Price, the federal Environment Minister, for again omitting climate change from the agenda of the regular gathering.
"The science is frightening, unequivocal and clear – we are running out of time," the Labor ministers said in a statement. "We must take swift and strong measures to reduce emissions now."
"Yet the response of successive Liberal prime ministers has been one of delusion and deliberate inaction – and it is unacceptable that any action on climate change has again been left off the agenda at todays meeting of environment ministers," they said.
Ms Price later told journalists that the ministers had had "a very good conversation", but could not agree on common wording. The minister will attend global climate talks in Poland from Sunday.
The environment ministers also secured only an agreement in principle over a national waste policy to deal with the country's mounting recycling issues after China limited waste imports.
NSW, Queensland and Victoria agreed to work together "to deliver real outcomes when it comes to waste", Gabrielle Upton, NSW Environment Minister, said.
"We disagree on many things, but on this issue, urgent national action is required," Ms Upton said. "The Commonwealth is now locked into playing a clearer real role in terms of leadership and funding."
Separately, the federal government has its "bioregional assessment" of the cumulative impacts on groundwater, creeks and rivers from opening central Queensland's Galilee Basin for mining.
Despite only modelling seven of 17 proposed coal and gas developments – including the Adani mine – the report predicted widespread impacts over 1.4 million hectares and as much as 6285 kilometres of streams.
“Given that the Suttor River is the target of Adanis plans to extract up to 12.5 billion litres of water per year, this should be enough to ensure that project is rejected once and for all," Lock the Gate, an anti-mining group, said in a statement.
“Its clear from this analysis that mining the Galilee Basin will have a very significant and irreversible impact on our water resources," including damaging as many as 181 wetlands, the group said.
Leeanne Enoch, Queensland's Environment Minister, said the Palaszczuk government "takes its environmental responsibilities very seriously and makes its decisions based on the best available science".
“At this point in time, the government is undertaking the work to allow consideration of the declaration of a cumulative management area over the Galilee Basin," Ms Enoch said.
“This allows government to consider the combined impacts of projects.”
Carmel Flint, a spokeswoman for Lock the Gate, said water was "the key to survival in such a dry region".
"The full scale of the water impacts exposed here should lead to urgent action by the Queensland government to reject the final water management plan which Adani are seeking to have approved before Christmas," she said.
Peter Hannam is Environment Editor at The Sydney Morning Herald. He covers broad environmental issues ranging from climate change to renewable energy for Fairfax Media.