Sept 5 (Reuters) - Australian shares fell on Tuesday, weighed down by commodity and banking stocks, as cautious traders awaited the central bank's key interest rate decision.

The S&P/ASX 200 index retreated 0.4% to 7,287.9 as at 0032 GMT. The benchmark ended 0.6% higher on Monday.

The Reserve Bank of Australia (RBA) is expected to keep rates unchanged when it meets later in the day, with inflation in the country showing signs of easing, according to a Reuters poll of economists.

"The guidance that 'some further tightening of monetary policy may be required' is likely to remain, and we think risks remain that the inflation data over the next couple of months could see the RBA act on that tightening bias" National Australia Bank analysts said in a note.

Mining stocks slid 1.0%, with sector majors BHP Group and Rio Tinto falling 0.5% and 1.1%, respectively.

Gold stocks retreated 1.4% to hit one-week lows.

Heavyweight banking stocks slipped 0.4%, with the "big four" banks falling between 0.1% and 0.5%.

Westpac Banking Corp was down 0.5% after Australia's corporate regulator said it was taking the lender to court over its alleged failure to respond to customers' financial hardship notices between 2015 and 2022, within the required administrative time frame.

Energy stocks fell 0.6%, with sector majors Woodside Energy and Santos falling 0.7% and 0.6%, respectively.

Packaging firm Orora Ltd said it would acquire French high-end glass bottle manufacturer Saverglass from private equity firm Carlyle Group for an enterprise value of A$2.16 bln ($1.40 bln). Orora shares are suspended from trading since Aug. 30.

Qantas Airways edged 0.2% higher, after Australia's flagship carrier said its long-serving CEO Alan Joyce would exit two months earlier than previously flagged as the company battles a reputational turbulence.

New Zealand's benchmark S&P/NZX 50 index retreated 0.4% to 11,472.15.

(Reporting by John Biju in Bengaluru; Editing by Rashmi Aich)