TORONTO (Reuters) - The Toronto Stock Exchange's main index closed lower yesterday as a retreat by resource issues and nagging worries over the health of the US economy ended two day's of gains.

NovaGold Resources and Teck Cominco Ltd. were among the biggest decliners by weight after the two mining companies halted their Galore Creek copper-gold-silver joint venture, largely due to soaring costs.

The materials sector, home to gold producers, was further hit as gold prices trimmed gains to step back from an earlier two-week high.

All but one of the TSX's 10 main groups were down, as investors continued to worry about global fallout from the crisis in US mortgage markets.

The S&P/TSX composite index closed down 146.15 points, or 1.1 percent, at 13,321.05.

The utilities sector was the sole group to end in positive territory, eking out a gain of 0.1 percent.

The materials group led the way down, losing 2.6 percent, while NovaGold dived C$10.71, or 53.7 percent, to C$9.25 and Teck skidded C$1.82, or 4.9 percent, to C$35.67.

The energy sector was down 0.9 percent, following a retreat by oil prices, which moved down 48 cents to $97.70 a barrel on expectations OPEC may increase output.

Petro-Canada was down C$1.08, or 2.1 percent, at C$50.52 and Suncor Energy fell C$1.90, or 1.9 percent, to C$99.44.

Financials were down 0.8 percent as the country's biggest banks get set to release fourth-quarter results.

Royal Bank of Canada was down 59 Canadian cents, or 1.2 percent, at C$49.46.

DundeeWealth Inc bucked the trend, edging higher after the mutual fund manager said it had formed a special committee of its board to review "expressions of interest" in buying the company.

DundeeWealth finished up 22 Canadian cents, or 1.1 percent, at C$21.00