North American markets started another week in the hole on persistent concerns about a trade war between the U.S. and China.

The S&P/TSX composite index closed down 103.57 points at 16,237.77.

In New York, the Dow Jones industrial average lost 391.00 points to 25,896.44. The S&P 500 index was down 35.96 points at 2,882.69, while the Nasdaq composite was down 95.73 points at 7,863.41.

The Canadian dollar traded for an average of US75.55¢ compared with an average of US75.64¢ on Friday.

The September crude contract was up US43¢ at US$54.93 per barrel and the September natural gas contract was down US1.4¢ at US$2.10 per mmBTU.

The December gold contract was up US$8.70 at US$1,517.20 an ounce and the September copper contract was down US0.4¢ at US$2.58 a pound.