*Billionaire Buffett's $5 bln bet helps sentiment
*Nexen rises, says production to dip due to Ike
*Energy, materials stocks gain on higher commodity prices
TORONTO, Sept 24 (Reuters) - The Toronto Stock Exchange's main index rose on Wednesday morning on strength in commodity stocks and a $5 billion investment in Goldman Sachs Group Inc (GS.N) by Warren Buffett's Berkshire Hathaway Inc (BRKa.N) (BRKb.N), but concerns over the fate of a U.S. government bailout plan for the financial industry lingered.
Berkshire Hathaway's purchase of a stake in Goldman Sachs helped to boost investor sentiment, said Francis Campeau, broker at MF Global Canada in Montreal, but markets remained cautious as U.S. lawmakers entered a second day of debate on the government's $700 billion financial rescue plan.
The U.S. government's push for quick congressional approval of the plan hit a major obstacle on Tuesday as some senators said the plan puts taxpayers at excessive risk. [ID:nN23313135]
Shortly after the open, the S&P/TSX composite index .GSPTSE was up 119.61 points, or 0.95 percent, at 12,652.24, with three of its 10 main groups higher.
The heavyweight energy sector was up 2 percent as oil edged higher to above $108 a barrel.
In the oil patch, Nexen Inc NXY.TO rose 2.9 percent higher to C$27.30. Late on Tuesday, Nexen said it expects significantly lower production volumes from its U.S. Gulf operations for the rest of the third quarter due to damage from Hurricane Ike. [ID:nBNG36200]
The materials group added 2.6 percent on firmness in metals prices. Among the gainers in the sector, Potash Corp of Saskatchewan (POT.TO) rose 4.2 percent to C$174.78, while Agnico-Eagle (AEM.TO) was up 4.3 percent at C$69.33.
Financials were flat with Royal Bank of Canada (RY.TO) up 0.9 percent at C$50.93. ($1=$1.03 Canadian) (Reporting by Jennifer Kwan; Editing by Peter Galloway)