MELBOURNE, Australia—When Ben Oliver and his partner Tamzin Dimmock appealed to their bank for a home loan early this year they received a surprisingly generous offer. Their bank calculated it could lend them about 850,000 Australian dollars (US$657,560)—over a third more than they needed to buy their two-bedroom Melbourne apartment.

“The hard part is getting the [collateral] together but once you are in the property game, it isn’t so bad,” said Mr. Oliver. Like other first-time buyers, the couple put none of their own money down on the apartment. The pair declined the full amount offered by the bank but they did roll in a car loan and credit-card debt to take advantage of record-low interest rates, the 32-year-old said.

Nearly nine years after a debt-fueled housing bubble burst in the U.S., helping tip the global economy into a recession it is still recovering from, some analysts worry Australia could have a bank crisis of its own.

Aggressive lending practices—including offering interest-only loans with little or no down payment—are starting to raise a red flag with credit-ratings firms, regulators and even Australia’s central bank. Their concern is that frothy house prices, combined with a rising debt burden, may leave Australia’s banks vulnerable to a housing-market correction as a long mining boom ends.

Australia’s banks appear among the sturdiest in the world, having sidestepped the financial crisis that drove many of their overseas peers into bankruptcy. The four biggest lenders— Commonwealth Bank of Australia Ltd., Westpac Banking Corp., Australia & New Zealand Banking Group Ltd. and National Australia Bank Ltd. —boast some of the highest credit ratings globally.