Australian shares have moved lower amid renewed concerns about US-China trade tensions.

The benchmark S&P/ASX200 index was down 33.4 points, or 0.53 per cent, to 6,262.3 points at 1200 AEST on Wednesday, while the broader All Ordinaries was down 35.3 points, or 0.55 per cent, to 6,348.2.

All sectors of the ASX were in negative territory at midday, with tech shares collectively tumbling 1.98 per cent to lead losses.

Afterpay Touch fell 5.45 per cent to $26.91, Wisetech Global slid 3.99 per cent to $22.15 and Xero lost 1.28 per cent to $53.36.

Consumer staples shares recorded the second-biggest drop, falling 0.96 per cent, dragged down by Treasury Wine Estate as it slumped 6.15 per cent to $15.175.

Coles was down 0.70 per cent to $12.72 but supermarket rival Woolworths gained 0.54 per cent to $32.525.

In the telco sector, TPG was up 2.99 per cent to $7.23 and Vodafone Hutchison added 3.13 per cent to 16.5 cents as the two companies waited for the Australian Competition and Consumer Commission to rule on their merger plan on Thursday.

Mining giant BHP was down 0.70 per cent to $37.04 and Rio Tinto was down 0.34 per cent to $95.72.

The big four banks were all lower, with ANZ down 0.07 per cent to $27.48, Commonwealth down 0.23 per cent to $74.44, NAB down 0.25 per cent to $25.775 and Westpac down 0.11 per cent to $27.03.

Comments from US officials overnight raised concerns among some investors that trade talks between China and the United States could take much longer to resolve than previously thought.

The Aussie dollar is buying 70.06 US cents, from 70.35 US cents on Tuesday.