TORONTO (Reuters) - Toronto's main stock index gained for the third-straight session yesterday, as a falling US dollar boosted commodity prices and sent shares of mining and energy companies higher.

Strong gold stocks led the TSX materials subgroup up 1.86 percent, while the more heavily weighted energy sector rallied 0.96 percent, as weak US housing data pressured the US greenback.

Four of the 10 main TSX groups ended the session higher.

"With the US dollar weakness, the Canadian dollar's strong, crude oil prices are up, natural gas prices are up. Pretty much across the board commodities are up," said Ian Nakamoto, director of research at MacDougall, MacDougall & MacTier.

Oil prices were also lifted by data showing US oil inventories fell more than expected last week.

Helping lift the energy sector were top players Suncor Energy, which rose 1.7 percent to C$37.13, and EnCana , which gained 1.7 percent to C$33.85.

In the materials group. which also benefited from surging copper prices, base metals miner Lundin Mining jumped 7.6 percent to C$4.27, while Goldcorp surged 3.5 percent to C$42.14.

The S&P/TSX composite index ended the session up 30.72 points, or 0.26 percent, at 11,658.7.

After falling sharply from a 14-month high hit on December 3, the index has been gradually regaining ground as tax-loss selling has abated, while recent economic data has built the thesis that the economy is on the mend.

Statistics Canada said yesterday that the economy grew for a second consecutive month in October, the first back-to-back gains since late 2007.

Nakamoto said that end-of-year "window dressing" - a rebalancing of mutual fund holdings - was likely behind the share moves of several companies, particularly as volumes wind down ahead of holidays.

The weakest sector was financials, down one percent, led by a Royal Bank of Canada, which fell 1.7 percent to C$55.57, and Toronto-Dominion Bank, which eased 1.4 percent to C$64.60.

The TSX will close for the Christmas and Boxing Day holidays at 1 p.m. today, reopening on Tuesday, December 29.