* TSX falls 24.27 points, or 0.19 percent, to 12,626.60 * Six of 10 sectors decline * BMO shares rise 1 percent after results By John Tilak TORONTO, Feb 26 (Reuters) - Canada's main stock index declined in volatile trading on Tuesday, with resource stocks tracking lower commodity prices and investors scrutinizing testimony by U.S. Federal Reserve Chairman Ben Bernanke. The declines were partially offset by Bank of Montreal , whose shares were up about 1 percent, after Canada's fourth-largest bank reported a core profit that topped expectations on the back of higher markets-related revenue. "It's a good sign for the rest of the banks," said Rick Hutcheon, president and chief operating officer at RKH Investments. The Toronto Stock Exchange's S&P/TSX composite index was down 24.27 points, or 0.19 percent, at 12,626.60, after opening higher. Six of the 10 main sectors on the index were in the red. In his testimony, Bernanke strongly defended the U.S. central bank's bond-buying stimulus before Congress, saying its benefits clearly exceed possible costs. The market is looking for the steady course of action from the Fed to continue, Hutcheon said. The uncertainty over the outcome of the Italian election was a drag on oil prices, which fell to a one-month low. As a result, energy shares fell 0.7 percent. Suncor Energy Inc, Canada's largest energy company, slipped 1.7 percent to C$30.85. The materials sector, which includes mining stocks, gave back 0.1 percent in choppy trading, with gold prices having a bumpy session. Financials, the index's weightiest sector, were little changed. Royal Bank of Canada, the country's biggest bank, fell 0.5 percent to C$63.28.