Canada's main stock index hit its lowest close in a month on Thursday as oil prices fell and investors sought refuge in safe-haven assets amid rising tensions between the United States and North Korea.

The influential financial stocks were among the biggest drags on the index, with Royal Bank of Canada (RY.TO) down 1.5 per cent to $92.88, and Manulife Financial Corp (MFC.TO) falling 4.7 per cent to $24.43, its largest drop since early August last year.

Shares of Manulife, which reported better-than-expected results, fell after the company played down talk of a John Hancock spin-off.

The overall financials group, which accounts for roughly a third of the index, declined 1.4 per cent, while energy shares also fell 1.4 per cent as oil prices turned down.

U.S. crude oil futures settled nearly two per cent lower at US$48.59 a barrel, as Russia considered a future output resumption and the Organization of the Petroleum Exporting Countries boosted its July production numbers.

The Toronto Stock Exchange's S&P/TSX composite index closed down 143.08 points, or 0.94 per cent, at 15,074.25, its lowest close since July 7. It was the biggest percentage loss since mid-June.

"I think the market was looking for a reason to come off here," said Irwin Michael, portfolio manager at ABC Funds. "The North Korea situation appears to be the culprit."

U.S. President Donald Trump ratcheted up his rhetoric toward North Korea on Thursday, saying the reclusive communist country should be "very, very nervous" if it even thinks about attacking the United States or its allies.

Materials, a sector that includes gold producers and other resource-based companies, was the lone gainer among the index's 10 main sectors, rising 0.7 per cent.

Barrick Gold Corp (ABX.TO) rose 2.3 per cent to $21.74 as the price of gold, a safe-haven asset, reached its highest levels in two months.

Pan American Silver Corp (PAAS.TO), which reported second-quarter results late Wednesday, rallied 10.7 per cent to $22.47.

Nevsun Resources Ltd (NSU.TO) offset some of the material group's gains, plunging 16.4 per cent to $2.75 after the company reported disappointing quarterly results.

In other corporate results, a number of companies reported forecast-beating numbers. TMX Group Ltd (X.TO) was up 3.2 per cent to $68.02, while Quebecor Inc (QBRb.TO) added 4.3 per cent to $45.20 and Canadian Tire Corp Ltd (CTCa.TO) climbed 5.7 per cent to $149.89.

"Generally, earnings are good ... it's our view that this pullback [in stocks] should provide good buying opportunities," ABC Funds' Michael said.