Sept 1 (Reuters) - Australian shares dropped on Wednesday, weighed down by banks and miners, as investors anticipated a sharp slowdown in economic growth ahead of June-quarter gross domestic product (GDP) data.

The economy was likely already slowing before wide-scale COVID-19 restrictions shuttered swathes of business and jobs, setting the stage for a vicious contraction this quarter, a Reuters poll showed.

Data released on Tuesday showed the country's current account surplus widened to a record high in the June quarter, due to booming prices for some key commodity exports, notably iron ore, and strong demand from China.

The S&P/ASX 200 index fell 0.8% to 7,474.9 by 0037 GMT, retreating from a two-week closing high marked on Tuesday.

Heavyweight financials dropped 0.6%, with all the "Big Four" banks — Commonwealth Bank of Australia, National Australia Bank, Australia and New Zealand Banking Group and Westpac Banking Corp — shedding between 0.1% and 1.1%.

Miners were weighed down by a drop iron ore prices, with Rio Tinto Ltd and BHP Group Ltd declining 1.7% and 1%, respectively.

Healthcare stocks also slipped, with sector giant CSL Ltd dropping 0.7%. Mesoblast fell for a second straight day after the biotechnology company said its annual attributable loss widened to $98.8 million.

Technology stocks fell, with buy now, pay later giant Afterpay Ltd and aerial imagery firm Nearmap shedding 1.4% and 0.9%, respectively.

Meanwhile, gold stocks nudged 0.1% higher, benefiting from an overnight rise in bullion prices.

New Zealand's benchmark S&P/NZX 50 index was down 0.2% at 13,195.36. Cancer diagnostics firm Pacific Edge Ltd was the top loser on the index.

Elsewhere, Japan's Nikkei rose 0.9%, while S&P 500 E-minis futures climbed 0.1%. (Reporting by Harish Sridharan in Bengaluru; Editing by Subhranshu Sahu)