* Sydney records worst pandemic day
* BHP, Rio fall 1.7% each; Fortescue down 3.4%
* CBA up 1.2%; will report full-year results next week
Aug 5 (Reuters) - Australian stocks closed at a record high on Thursday, with banks leading the gains ahead of next week's earnings from two of the "Big Four" lenders.
The S&P/ASX 200 index ended up 0.1% to 7,511.1, marking an all-time high finish for the third time this week.
The "Big Four" banks climbed between 0.2% and 1.2%. Commonwealth Bank of Australia, the country's largest, gained the most ahead of its results next week where it is expected to announce a share buyback.
Miners were the biggest losers, falling 1.6%, with Rio Tinto and BHP Group shedding around 1.7% each. Fortescue Metals Group dropped 3.4%.
A sharp drop in iron ore prices due to soft Chinese demand weighed on the sector.
"There is nervousness around some of the iron ore names, with China flexing its muscles. But we are seeing enhanced trends around the growth of battery metals sector and talk of decarbonisation," said Damian Rooney, director of equity sales at Argonaut.
Worries about the COVID-19 situation also capped gains, with Sydney recording its worst day of the pandemic.
Energy stocks fell 1.2% to close at its lowest since May 31.
Papua New Guinea's Prime Minister James Marape said on Thursday the potential takeover of Oil Search by Australia's top natural gas producer Santos Ltd's could produce high value for the country but should satisfy "national interest".
Tech stocks, meanwhile, edged higher. Analytics firm Nuix Ltd was the top gainer on both the benchmark and , with Xero Ltd following with a 2.2% jump.
The gold index ended 0.4% lower. However, Resolute Mining gained 4.5% after saying it would sell its Ghana mine to Canada's Asante Gold Corp for $90 million.
New Zealand's NZX 50 index slipped 0.3% to 12,753.76.
Polymer products manufacturer Skellerup Holdings Ltd was the top percentage gainer, up 2.2%. (Reporting by Yamini C S in Bengaluru; editing by Uttaresh.V)
