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By Matt Siegel
CANBERRA, Dec 15 (Reuters) - Australia's government on Tuesday forecast its budget deficit would swell to A$37.4 billion ($27.13 billion) in the year to June as falling prices for key resource exports open a gaping hole in tax revenue.
Treasurer Scott Morrison predicted the shortfall for 2016/17 would be A$33.7 billion.
The deficit for 2015/16 had been forecast at A$35.1 billion in the May budget, while the 2016/17 shortfall had been seen at A$25.8 billion.
The data marks the first major financial stumbling block for Prime Minister Malcolm Turnbull, who ousted Tony Abbott in a September party coup sparked partly by his inability to sell his economic vision for the country.
Plummeting commodity prices have depleted the government's coffers, although analysts have expressed little concern that the poor showing will threaten Australia's coveted triple-A credit rating.
Morrison defended the government's handling of the economy, blaming the free fall in iron ore prices on which previous budget estimates had been based, rather than economic mismanagement, for the poor showing.
"The price we are able to achieve in global markets in iron ore went from a high of A$180 a tonne to A$38, A$39 a tonne at the moment," Finance Minister Mathias Cormann told reporters in Perth.
"When iron ore is about 20 percent of our national export income, of course you'd expect that to flow through."
Morrison added, however, that policies aimed at moving away from an overreliance on commodity exports towards a more services and tech-based economy were already being implemented and represented the country's future.
That sort of language marks a shift from Abbott, who was known as a vigorous advocate for the coal industry, in particular.
"The destination we are heading towards is a more diversified economy where the impact of things like the iron ore price in the future will not have the result that it has in these figures in the future because we'll have a more diversified economy," Morrison said.
Australia is forecasting net debt to peak at 18.5 percent of gross domestic product (GDP) in the year to June 2018, before gradually declining, with unemployment topping out at 6 percent this year.
While the figures may seem gloomy for Australia, which survived the global financial crisis relatively unscathed, they would be enviable for many of its western peers and is unlikely to alter the ratings agencies' views, in particular.
"The budget update, which as discussed, is expected to leave bigger deficits over the coming four years, is unlikely to be severe enough to cause the ratings agencies to change their overall view of Australia," ANZ ANZ.AX bank wrote in a note on Monday.
Rating agency Standard & Poor's said on Tuesday the next six months would be important for Australia's budget outlook with tax reform under consideration and spending cuts jammed in the Senate.
"The next six months could have significant implications for Australia's budget outlook," said S&P.
($1 = 1.3784 Australian dollars)