The Australian stock market was slightly firmer at Wednesday noon, boosted by mining gains on the back of higher metals prices overnight.

At midday AEST, the benchmark S&P/ASX200 index lifted 0.22 per cent to 4,680.4 points, while the broader All Ordinaries index had added 0.2 per cent to 4,726.5 points.

On a sector-by-sector basis, telecoms gave the best performance, advancing 1.07 per cent, as Telstra said it could maintain its dividend and was hopeful that an NBN deal would be reached soon.

This was followed by materials and utilities, which improved 0.91 and 0.24 per cent respectively. Meanwhile, information technology, consumer staples and financials lost ground, shedding 0.555, 0.46 and 0.2 per cent.

The major miners drove gains, with BHP Billiton, Rio Tinto and Newcrest doing most of the heavy lifting.

BHP Billiton was up 1.03 per cent to $39.84 after announcing plans to stretch its Olympic Dam expansion into three phases, each costing around $5.2 billion.

Rio Tinto swelled 1.06 per cent to $77.82 and gold producer Newcrest Mining gained 1.52 per cent to $39.98, after the price of gold soared to a new record high overnight.

The spot price of gold in Sydney was $US1308.50 an ounce, up $US16.80 from $US1291.70 an ounce yesterday. It earlier reached a record $US1309.95.

The big four banks were mixed, as ANZ Banking Group was flat at $24.30, Commonwealth Bank of Australia edged down 0.24 per cent to $52.47, National Australia Bank stepped up 0.42 per cent to $26.25 and Westpac Banking Corp turned down 0.33 per cent to $23.94.

Meanwhile, investment bank Macquarie Group lifted 0.42 per cent to $37.46.