* TSX falls 66.25 points, or 0.6 percent, to 11,797.31
* Eight of 10 sectors lower (Updates with details, commentary)
By Claire Sibonney
TORONTO, Aug 10 (Reuters) - Toronto's main stock index stumbled on Tuesday morning after soft U.S. and Chinese economic data weighed on already cautious sentiment ahead of a U.S. Federal Reserve monetary policy meeting later in the day.
Worried investors flocked to the safe haven of U.S. dollar, which dragged down commodity prices and Toronto's resource-loaded index.
The materials sector was down 0.8 percent after copper and gold prices declined. First Quantum Minerals (FM.TO) slipped 1.7 percent to C$64.88 ahead of its quarterly results, and Barrick Gold Corp (ABX.TO) was down 0.8 percent at C$44.13.
Energy stocks were 0.6 percent lower as oil dropped more than $2 to below $80 a barrel, pulling down Canadian Natural Resources (CNQ.TO) by 1.7 percent to C$36.24.
Uncertainty has been building over the U.S. recovery and investors are looking to see what measures, including printing more money, the the Fed might take to prop up a faltering economy. [ID:nN09275781]
Data showed an unexpected drop in U.S. non-farm productivity in the second quarter, the first decline since late 2008, underlining the softening pace economic recovery. As well, China reported a much slower than expected growth in July imports, signaling slowing domestic demand. [ID:nN10131732] and [ID:nTOE67904G]
"We've seen a bit of optimism over the last few weeks here and now we're kind of confronted with some of the fundamentals on the economic side and at the same time some monetary stimulus decisions, so there's quite a bit on the plate today," said Youssef Zohny, associate portfolio manager at Van Arbor Asset Management, in Vancouver.
"Expectations are fairly high for the Fed to at least acknowledge that there's some risk on the economic and price side and maybe hint at some future actions. Anything less than that I think will probably be a disappointment," Zohny said.
At 10:28 a.m. (1428 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 66.25 points, or 0.6 percent, at 11,797.31. Eight of the 10 sectors were down, with healthcare and technology stocks slightly higher.
Among the biggest gainers on the TSX was Research in Motion RIM.TO, which jumped 2.1 percent to C$57.99 after the BlackBerry maker won a reprieve from a threatened ban on its Messenger texting service as Saudi Arabia said progress was being made on addressing its concerns over access to RIM's encrypted systems. [ID:nLDE6790DY]
In other individual company news, PetroBakken Energy PBN.TO fell 2 percent to C$21.59 after reporting a wider quarterly loss and said its drilling activities in Alberta were hurt by wet weather. [ID:nSGE6790EI]
Sino-Forest TRE.TO lost 1.9 percent to C$16.82, despite posting quarterly results above market estimates, helped by higher average selling prices of standing timber, as well as an increase in its log-trading business. [ID:nSGE66S0H3]
$1=$1.04 Canadian Reporting by Claire Sibonney; editing by Rob Wilson