The value of Canadian wholesale trade unexpectedly jumped in July, making for the biggest increase in six months as gains were seen across several sectors, including building materials and food, data from Statistics Canada showed on Thursday.

The 1.5 per cent increase exceeded economists' forecasts for a decline of 0.9 per cent and was the biggest increase since January. June's figures were downwardly revised to show a decrease of 0.6 per cent from an initially reported 0.5 per cent decline.

Stripping out the effects of price changes, July volumes were even stronger, up 2.1 per cent, the largest gain since December 2016.

The surprise increase could bolster expectations for July gross domestic product and offset a decline in manufacturing sales earlier this week.

Attention will likely turn to Friday's retail sales data to see how growth at the start of the third quarter is shaping up after a strong first half of the year.

Sales rose in five out of seven sectors, accounting for 86 per cent of total sales. The building material industry led the way with a 4.8 per cent increase, helped by improved sales of lumber and other building supplies.

Sales rose 2.4 per cent in the food, beverage and tobacco sector, recovering from a decline in the previous month as all three of the category's industries increased.

The vehicle and parts sector rose 1.4 per cent on stronger sales of vehicles. Auto sales in Canada have been strong so far this year and could put 2017 on track to hit a record.