Canada's main stock index fell on Wednesday, with the broad retreat accelerating in afternoon trade after Reuters reported that Canada is increasingly convinced the United States will withdraw from the North American Free Trade Agreement.

The Toronto Stock Exchange's S&P/TSX composite index ended the day down 71.29 points, or 0.44 percent, at 16,247.95.

Railways, pipelines and other trade-sensitive stocks including auto parts maker Magna International Inc were among the heaviest weights, after two government sources said U.S. President Donald Trump could announce he intends to pull out of the trade deal this month, when negotiators from the two countries and Mexico are due to resume talks.

Canadian National Railway Co (CNR.TO) lost 2.7 per cent to $101.87 and rival Canadian Pacific Railway (CP.TO) Ltd fell 3.1 per cent to $225.52, while TransCanada Corp (TRP.TO) shed 2.4 per cent to $59.57 and fellow pipeline company Enbridge Inc (ENB.TO) was down 2.1 per cent at $49.11. Magna (MG.TO) fell 3.2 per cent to $71.44.

Nine of the index's 10 main sectors ended lower, with gains for gold miners helping boost the materials group, which also includes base metals miners and fertilizer companies.

Gold hit its highest in nearly four months as the U.S. dollar swooned after a report that Chinese officials had recommended slowing or halting purchases of U.S. Treasury securities.

Media company Corus Entertainment Inc (CJRb.TO) slumped 16.9 per cent to $9.17 after disappointing quarterly results that led an analyst at RBC Capital Markets to make a "major recalibration" of his forecast for Corus' television revenue.

Miner Klondex Mines Ltd (KDX.TO) lost 11.5 per cent to $2.62 after announcing it would pull back on operations at its True North project in Manitoba.

The energy group retreated 0.1 per cent, although Crescent Point Energy Corp (CPG.TO) rose 4.5 per cent to $10.94 as analysts at two banks increased their price targets on the stock following the release of the company's 2018 budget.

Oil prices  hit fresh multi-year highs as OPEC-led production cuts and healthy demand helped balance the market, but analysts warned of possible overheating.