Australian shares have fallen to their lowest level in over a month as investors sold out of equities in response to renewed economic concerns in the US.

The benchmark S&P/ASX200 index was down 61.2 points, or 1.4 per cent, at 4,320.1, while the broader All Ordinaries index was down 61.8 points, or 1.4 per cent, at 4,356.6. Both indices were at their lowest closing levels since July 8.

On the Sydney Futures Exchange, the September share price index contract was 65 points lower at 4,304 on volume of 33,954 contracts.

In the banking sector, National Australia Bank declined 42 cents to $22.77, Westpac dropped 37 cents to $21.06, ANZ lost 45 cents to $22.19 and Commonwealth Bank shed $1.15 to $48.30.

The only bright spot in financials was Suncorp-Metway, which posted a 19 cent rise to $7.97 after posting a $780 million annual net profit, more than double that of the previous year.

In resources, Rio Tinto lost $1.62 to $69.45 and BHP Billiton dropped 10 cents to $37.44 ahead of the release of its full year results due after the market close.

Investors punished WorleyParsons after it posted a 25 per cent fall in annual profit, despite being within the engineering group's guidance. Its shares lost $2.04, or 9.17 per cent, to $20.20.

Among the day's better performers was Pacific Brands, with a return to annual profit and a positive outlook pushing its shares up 11 cents, or 12.43 per cent, to 99.5 cents.

Airport owner MAp Group gained 11 cents, or 3.85 per cent, to $2.97 after it returned to half year profit and said air traffic growth would be strong in the short term.

Several healthcare stocks also outperformed, with Sonic Healthcare up 20 cents to $11.00 after a broker upgrade and CSL gaining 21 cents to $31.41. The spot price of gold in Sydney was $1,233.00 per fine ounce, up $11.77 on Tuesday's closing price of $1,221.23 per ounce.

Lihir Gold stocks lost five cents to $4.40 and Newcrest shed 24 cents to $35.49. The top traded stock by volume was Focus Minerals, with 51.7 million shares worth $2.18 million changing hands.

Shares in Focus lost 0.1 cent, or 2.33 per cent, to 4.2 cents. Preliminary market turnover was 2.17 billion shares worth $6.3 billion, with 352 stocks up, 748 down and 328 unchanged.

The Australian dollar was weaker late Wednesday in Asia on poor U.S. home sales data, a ratings downgrade for Ireland and amidst continuing political uncertainty domestically. The Australian dollar was quoted at $0.8817, down from $0.8887 late Tuesday. Against the Japanese yen, the Australian dollar was at 73.985, from 75.51.