The Australian stockmarket was flat at Tuesday noon, as investors took extra caution while waiting for the Reserve Bank of Australia's move on rates and a possible announcement on which political party will rule.

At 1205 AEST, the benchmark S&P/ASX200 index added 0.16 per cent to 4,583.1 points. The broader All Ordinaries gained a moderate 0.17 per cent to 4,623.8 points.

Materials stocks increased 0.1 per cent, industrials eased 0.2 per cent and the financials index went up 0.1 per cent.

The market was drifting, with small gains to financials, as investors were on guard ahead of an RBA interest rate decision, according to Jamie Spiteri, a senior dealer with Shaw Stockbroking.

Another factor that may also weigh on investors' minds is a possible decision by key independent members of parliament on which party they will support to take power in Australia. The announcement is anticipated at 2pm AEST.

The big four banks were all less than one per cent higher at noon, with ANZ Banking Group lifting 0.54 per cent to $23.79, Commonwealth Bank of Australia approaching 0.46 per cent to $52.36, National Australia Bank moving forward 0.28 per cent to $24.35 and Westpac Banking Corp edging up 0.36 per cent to $22.93.

After taking a battering in Monday's trade following a profit downgrade, investment bank Macquarie Group was again pushed lower, and sank 1.98 per cent to $34.55.

The major iron ore miners remained uncertain, as BHP Billiton firmed up 0.18 per cent to $38.62, while Rio Tinto slid 0.49 to $74.63 and Fortescue Metals Group grew 0.8 per cent to $4.98.

Gold miner Newcrest Mining was little changed at $38.16.

Among the oil companies, Woodside Petroleum edged up 0.43 per cent to $43.59. Santos looke up 0.5 per cent to $13.86 and Oil Search shed 0.33 per cent to $5.95.