Australia’s AAA rating remains unchanged despite the federal government handing down an $18 billion deficit.

The world’s two largest ratings agencies have retained Australia’s AAA rating due to the nation’s low public debt and prudent fiscal policy in the medium term.

In a statement, Moody’s said the outlook for Australia remained strong as the projected budget deficits were only a small percentage of GDP.

Although the government budget is now forecast to remain in deficit through the 2014-15 fiscal year, the projected deficits are relatively small as a percentage of GDP,’’ Moody’s said.

‘‘As a result, the ratio of government debt to GDP will rise only marginally, and Australia will remain among the few AAA-rated sovereign debt issuers that have low debt levels.’’