Aug 12 (Reuters) - New Zealand stocks registered their worst close in a month on Wednesday after the country reported its first set of coronavirus cases in 102 days, while losses among miners and gold stocks weighed down on the Australian bourse.

The New Zealand benchmark S&P/NZX 50 index fell 1.3% to 1,491.91 at the end of trade, hurt by losses across almost all sectors.

Prime Minister Jacinda Ardern delayed a key step toward next month's general election as the country was plunged into lockdown on discovering its first COVID-19 cases in more than three months.

"The lockdown has come as a big shock to citizens and investors alike... there was a real sense earlier that New Zealand had beaten the virus," said Michael McCarthy, chief market strategist at CMC Markets.

Meanwhile, the Reserve Bank of New Zealand expanded its bond-buying programme and warned that policy rates might have to go below zero to revive its economy.

Among stocks, dairy processor Synlait Milk fell 0.9% and utilities company Meridian Energy dropped 2.7%.

The Australian benchmark S&P/ASX 200 index fell 0.1% to 6,132.0 at the close of trade, as data showed wages grew at their slowest pace on record in the second quarter, while a measure of consumer sentiment fell sharply in August.

Heavyweight miners BHP Group, Fortescue Metals Group and Rio Tinto fell between 0.7% and 1.4% after iron ore prices slumped.

The subindex for gold stocks dropped more than 4%, as prices of the yellow metal continued to fall against a resurgent dollar, with the country's largest-listed gold miner Newcrest Mining tumbling 3.2%

Commonwealth Bank of Australia fell 0.5% after Australia's largest lender slashed its annual dividend by more than half, even as its full-year cash profit fell 11%.

Three of the other "big four" banks - Westpac Banking , National Australia Bank and Australia and New Zealand Banking Group - rose between 2% and 2.3%.

(Reporting by Soumyajit Saha in Bengaluru; Editing by Amy Caren Daniel)