Two tweets by Donald Trump have tanked the local bourse – along with markets around the globe – as investors worried the US-China trade war might not be so close to resolution after all.

The benchmark S&P/ASX200 index closed down 52.1 points, or 0.72 per cent, to 6,283.7 points at 1615 AEST on Monday, while the broader All Ordinaries was down 57.3 points, or 0.89 per cent, to 6,369.9.

The Aussie dollar is buying 69.91 US cents, from 69.95 US cents on Friday.