Australia shares hit more than four-week low BHP sees worst day...

• Australia shares hit more than four-week low
• BHP sees worst day in nearly seven months
• Consumer staples buoy New Zealand shares

(Updates to close)

Jan 17 (Reuters) - Australian shares slipped to a more than four-week low on Wednesday, extending its second straight session of losses as material stocks slumped on weak base metal prices.

The S&P/ASX 200 index (xjo) fell 0.5 percent, or 32.8 points, to 6,015.8 at the close of trade.

Australia's metals and mining index .AXMM slid as much as 2.4 percent, posting its biggest fall in over four months.

Mining giant BHP Billiton Ltd (BHP) fell 2.9 percent, posting its worst day in nearly seven months, while Rio Tinto (RIO) slipped 3.5 percent.

Chinese iron ore future fell for a fifth day running on Wednesday, while Shanghai aluminium prices extended declines into a second day. [MET/L] [IRONORE/]

The country's financial sector .AXFJ, which constitutes about 40 percent of the Aussie index, was down 0.3 percent, with the 'Big Four' banks slipping in the range of 0.3 percent to 0.6 percent.

Meanwhile, Sirtex Medical Ltd (SRX) was the top gainer on the benchmark, jumping 13.9 percent to hit a more than nine-month high after forecasting strong half yearly results.

Software developer Wisetech Global Ltd (WTC) rose 3.6 percent to a one-week high, while real estate stock Shopping Centres Australasia Property Group RE Ltd (SCP) gained 1.4 percent.

New Zealand's benchmark S&P/NZX 50 index (nz50) extended gains in its second straight session, rising 0.6 percent, or 47.13 points, to close at 8,297.67.

Consumer staples were the biggest gainers on the index with Synlait Milk (SML) adding 3.7 percent and a2 Milk Company (ATM) jumping over 3 percent.

Global dairy prices climbed 4.9 percent in the second auction of the year as buyers anticipate supply issues because of unusually dry weather in New Zealand, the world's largest milk exporter.