Australia's economy has overtaken Spain's to become the 12th-largest in the world, according to the Government's analysis of new International Monetary Fund (IMF) data.

Treasurer Wayne Swan has described the result as a "remarkable achievement" given Australia's relative population size.

"Since the Government came to office, Australia has moved up three places from 15th-largest economy to now be the 12th-largest economy in the world," Mr Swan said.

"Since 2007, Australia's economy has surpassed the economies of South Korea, Mexico and now Spain.

"These are three very different economies from three very different parts of the world, further highlighting the exceptional performance of our economy."

The comparisons are based on a country's gross domestic product expressed in the current exchange rate for the US dollar.

But it comes as the IMF cuts the growth outlook for the global economy and warns that while the recovery is continuing, it has weakened.

It says the debt crisis in the eurozone remains the most obvious threat to the global outlook and unemployment is likely to remain "elevated" in many parts of the world.

Despite the gloomy predictions, Mr Swan says the Government remains on track to deliver a surplus this financial year.

"The Australian economy remains the standout performer of the developed world, with solid growth, low unemployment, contained inflation, strong public finances and an enormous pipeline of investment in resources which is boosting our economic capacity and export volumes," Mr Swan said in a statement.

The Treasurer is due to deliver a budget update before the end of the year, which is expected to include significant spending cuts given the continuing decline in company tax receipts.