* TSX up 26.75 pts, or 0.2 pct, to 12,727.13
* Materials, financials lift index
* SNC Lavalin shares plunge 22 pct
* U.S. economic data weighs
* New round of ECB loans lifts hope
By Jon Cook
TORONTO, Feb 28 (Reuters) - Toronto' main stock index was higher at midday on Tuesday as resource issues rose on higher metals and oil prices, shrugging off disappointing U.S. economic data and some soft earnings.
The index's heavily weighted materials group led gains, rising 1 percent as mining issues benefited from higher gold, silver and copper prices.
Goldcorp led gold producers, rising 2 percent to C$49.30 as bullion rose towards $1,800 an ounce. A similar rally in silver prices pushed Silver Wheaton shares up 2.7 percent to C$39.61.
Fertilizer producer Potash Corp, which climbed 1.2 percent to C$46.97, also boosted gains.
At noon (1700 GMT), the Toronto Stock Exchange's S&P/TSX composite index was up 26.75 points, or 0.2 percent, to 12,727.13.
Energy issues reversed and rose 0.2 percent as oil prices seesawed on Tuesday with investors weighing the threat to demand from high prices against supply concerns and anticipation of more liquidity injections from the European Central Bank, which were expected to support petroleum futures.
Top oil and gas producer Suncor Energy led the way, rising 0.9 percent to C$36.48.
Energy sector gains were hurt by Petrominerales Ltd , which plunged more than 7 percent to C$17.61 a day after the South America-focused oil and gas producer said production from its assets in Colombia and Peru fell in January as the company dealt with two off-line wells.
Gains were limited as investor faith in the U.S. economic recovery was tested after data on Tuesday showed durable goods orders fell in January by the most in three years and home prices declined in December.
While the durable goods data was disappointing, analysts did not think it was a game changer.
"The U.S. economy will still continue to improve, but it's slow growth economy, maybe 2 to 3 percent GDP growth," said Pat McHugh, Canadian equity strategist at Manulife Asset Management.
In Canada, a profit warning by SNC-Lavalin Group Inc and soft earnings by miner Thompson Creek Metals also dragged, but were offset by decent earnings by Bank of Montreal.
SNC-Lavalin Group was the index's worst performer on Tuesday, tumbling more than 21 percent to C$37.86 after the engineering and construction company warned its net income for 2011 would come in about 18 percent below its previous forecast.
Shares of Thompson Creek Metals sank nearly 13 percent to C$7.56 on Tuesday, a day after the molybdenum miner reported soft fourth-quarter earnings and said development costs at its Mt Milligan copper project would rise by 10 to 20 percent.
Financial issues rose 0.4 percent, pushed higher by BMO's better-than-expected rise in quarterly earnings, driven by lower losses for bad loans and its acquisition of Wisconsin lender Marshall & Ilsley last year. BMO shares were up 0.7 percent at C$58.44.