* TSX falls 23.01 points, or 0.18 percent, to 12,717.49 * Six of the 10 main index sectors advance * Gold miners shed nearly 2 percent as bullion weakens By John Tilak TORONTO, Sept 4 (Reuters) - Canada's main stock index fell on Wednesday as a weaker bullion price weighed on gold-mining shares and worries about possible military action in Syria hit sentiment, overshadowing bullish economic data from Europe and China. The Toronto stock market's benchmark index touched a three-month high the previous session. Surveys released on Wednesday showed Chinese service-sector growth reached a five-month high in August and euro zone businesses recorded their best month in August in more than two years. Those figures followed strong U.S. manufacturing data on Tuesday. With economic data looking stronger, investors were bracing for the U.S. Federal Reserve to dial back its monetary stimulus program. The market was also preparing itself for an increase in tension in the Middle East after President Vladimir Putin indicated that Russia does not rule out support for using force against Syria. "The biggest issue for investors is the uncertainty, and markets hate uncertainty," said Rick Hutcheon, president and chief operating officer at RKH Investments. "We don't know if the Americans are going to attack, we don't know if anyone is going to do anything." "All this is doing is providing an overlay of uncertainty in a market that is trying to come to terms with the economic realities of the U.S. and European economic recoveries." The Toronto Stock Exchange's S&P/TSX composite index was down 23.01 points, or 0.18 percent, at 12,717.49. Six of the 10 main sectors on the index were higher. The materials sector, which includes mining stocks, gave back 1.3 percent. The price of bullion dropped 1 percent, dragging producers of the commodity down 2 percent. Goldcorp Inc dropped 1.2 percent to C$31.04, and Barrick Gold Corp declined 1.4 percent to C$20.23. Financials, the index's most heavily weighted sector, were little changed, with a 0.3 percent gain in Toronto-Dominion Bank offset by a 0.4 percent decline in Royal Bank of Canada .