Federal Labor won't be satisfied with any evidence Treasury boss Martin Parkinson provides to a Senate hearing that backs up the case for a big hike in the government's debt ceiling.
Mr Parkinson faces a budget estimates hearing in Canberra on Wednesday amid debate about Treasurer Joe Hockey's bid for a $500 billion cap on government borrowings.
Opposition finance spokesman Tony Burke says Labor will need more than words from the Treasury secretary to alter its backing for a $400 billion limit, up from the current cap of $300 billion.
It wants Mr Hockey to release the mid-year budget review and forecasts before another parliamentary vote is taken on the debt ceiling.
"It should be released and put on the table," he told reporters in Canberra.
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"No one gets an increase in their credit limit without providing any paperwork."
The Australian Greens say it is up to the government, not its bureaucrats, to make the case for raising the debt ceiling.
"There's a worrying trend in this government where they are hiding behind the people implementing their policies," deputy leader Adam Bandt told reporters.
"We need to hear in one form or another what the government wants to spend the money on."
The Greens also want the government to explain why it is repealing the mining tax but going "cap in hand" to parliament asking for more cash.
Parliamentary secretary Steve Ciobo said the coalition had a different approach to Labor and the Greens, who "just wanted to kick the can down the road" like the United States.
"We want to deal with this issue once, we want to put it behind us," he told reporters, adding the government needed to provide certainty for Australian and global markets.
Mr Ciobo argued the government needed the bigger cap because "we don't know what else is going to happen".
"Obviously this is a period of economic tumult," he said.
