SYDNEY - Australians voted on Saturday in the closest general election in decades with voters deeply divided on whether to give Labor a second term or opt for conservative rule, raising a real prospect of a minority government.

At stake was not only the political future of Prime Minister Julia Gillard and the opposition's Tony Abbott, both new and untested leaders, but also Labor's plans for a 30% resource tax and a $38 billion broadband network.

Abbott's Liberal-National coalition, which ruled for 12 years before Labor won the last election in 2007, has pledged to scrap Labor's three key policies: a new mine tax, fiber-optic broadband and a future carbon price to tackle climate change.

Financial markets were unsettled by the possibility of a hung parliament, where no major party wins enough votes to form government in their own right. Such a scenario would see the Australian dollar sold off and possibly result in policy gridlock and investment paralysis.

Without a clear winner, the next government would have to rely on a handful of independent or Green MPs to form rule.

About 40% of Australia's share market is owned by foreign investors and the uncertainty helped put pressure on the Australian dollar on Friday. One financial analyst has tipped a fall of between 2% and 5% in the currency if a minority government is elected.

The latest opinion poll by the Sydney Morning Herald and The Age newspapers showed Labor narrowly ahead.

With no dominant election theme, the vote is expected to be decided on various issues in important marginal seats, mainly in the resource states of Queensland and Western Australia and the mortgage belts of Sydney and Melbourne.

Gillard paid a last visit to crucial marginal seats in western Sydney on Saturday.

"I think people know I've got a passion for work, for supporting jobs, a passion for making sure every child gets a decent education," she said. "I think people have seen that on display. They can now judge my policies."

A uniform swing of only 1.7% would unseat Labor.

"There is still a lot of work to be done," said Abbott as he cooked breakfast sausages at a Sydney surf club before voting.

In a unique poll with an Australian twist in the city of Darwin, a 4.9 meter (16 ft) saltwater crocodile, which last month tipped Spain to win the soccer World Cup, predicted a Gillard win by chomping on a chicken carcass dangled below her image.